Bahais generally treat scriptural language as figurative and symbolic, and the same is true of Satan, the Devil, Beelzebub and so forth. I for one don't think they literally exist!

Abdu'l-Baha says

"...it is possible that one thing in relation to another may be evil, and at the same time within the limits of its proper being it may not be evil. Then it is proved that there is no evil in existence; all that God created He created good. This evil is nothingness; so death is the absence of life. When man no longer receives life, he dies. Darkness is the absence of light: when there is no light, there is darkness. Light is an existing thing, but darkness is nonexistent. Wealth is an existing thing, but poverty is nonexisting.
Then it is evident that all evils return to nonexistence. Good exists; evil is nonexistent."

    (Abdu'l-Baha, Some Answered Questions, p. 264)

And in a letter to one of the Friends he say:

"Give greeting to thy dear mother. Superstition hath somewhat overcome her. When the imagined Satan overpowers, let her say: "O Baha-el- ABHA!" She should then turn to the highest Kingdom. Thus will the imagined Satan leave her. [She] has a form of obsession; therefore, you may not heed her sayings.
Cultivate the land and thus, through its fruits, you will obtain benefits."
    (Abdu'l-Baha, Tablets of Abdu'l-Baha v1, p. 103)

I like the last bit: a spot of gardening brings one down to earth, and then our mental obsessions are put in proportion.

In another Tablet, he writes (and note the last bit):

O ye loved ones of God! In this, the Bahá'í dispensation, God's Cause is spirit unalloyed. His Cause belongeth not to the material world. It cometh neither for strife nor war, nor for acts of mischief or of shame; it is neither for quarrelling with other Faiths, nor for conflicts with the nations. Its only army is the love of God, its only joy the clear wine of His knowledge, its only battle the expounding of the Truth; its one crusade is against the insistent self, the evil promptings of the human heart.
    (Abdu'l-Baha, Selections from the Writings of Abdu'l-Baha, p. 256)

when it mentions in the bible that eve was tempted by the devil - what  is the explanation of that?

Adam signifies the heavenly spirit of Adam, and Eve His human soul. For in some passages in the Holy Books where women are mentioned, they represent the soul of man. The tree of good and evil signifies the human world; for the spiritual and divine world is purely good and absolutely luminous, but in the human world light and darkness, good and evil, exist as opposite conditions.

The meaning of the serpent is attachment to the human world. This attachment of the spirit to the human world led the soul and spirit of Adam from the world of freedom to the world of bondage and caused Him to turn from the Kingdom of Unity to the human world. When the soul and spirit of Adam entered the human world, He came out from the paradise of freedom and fell into the world of bondage. From the height of purity and absolute goodness, He entered into the world of good and evil.

The tree of life is the highest degree of the world of existence: the position of the Word of God, and the supreme Manifestation. Therefore, that position has been preserved; and, at the appearance of the most noble supreme Manifestation, it became apparent and clear. For the position of Adam, with regard to the appearance and manifestation of the divine perfections, was in the embryonic condition; the position of Christ was the condition of maturity and the age of reason; and the rising of the Greatest Luminary [Baha'u'llah] was the condition of the perfection of the essence and of the qualities. This is why in the supreme Paradise the tree of life is the expression for the center of absolutely pure sanctity -- that is to say, of the divine supreme Manifestation....

This attachment of the soul and spirit to the human world, which is sin, was inherited by the descendants of Adam, and is the serpent which is always in the midst of, and at enmity with, the spirits and the descendants of Adam. That enmity continues and endures. For attachment to the world has become the cause of the bondage of spirits, and this bondage is identical with sin, which has been transmitted from Adam to His posterity. It is because of this attachment that men have been deprived of essential spirituality and exalted position.

('Abdu'l-Baha, "Some Answered Questions, p. 123-125)