the verse in question is from 2:282
"O ye who believe! When ye deal with each other, in transactions involving future obligations in a fixed period of time, reduce them to writing Let a scribe write down faithfully as between the parties: let not the scribe refuse to write: as God Has taught him, so let him write. Let him who incurs the liability dictate, but let him fear His Lord God, and not diminish aught of what he owes. If the party liable is mentally deficient, or weak, or unable Himself to dictate, Let his guardian dictate faithfully, and get two witnesses, out of your own men, and if there are not two men, then a man and two women, such as ye choose, for witnesses, so that if one of them errs, the other can remind her. The witnesses should not refuse when they are called on (For evidence). Disdain not to reduce to writing (your contract) for a future period, whether it be small or big-long-: it is juster in the sight of God, More suitable as evidence, and more convenient to prevent doubts among yourselves but if it be a transaction which ye carry out on the spot among yourselves, there is no blame on you if ye reduce it not to writing. But take witness whenever ye make a commercial contract; and let neither scribe nor witness suffer harm. If ye do (such harm), it would be wickedness in you. So fear God; For it is Good that teaches you. And God is well acquainted with all things. If ye are on a journey, and cannot find a scribe, a pledge with possession (may serve the purpose). And if one of you deposits a thing on trust with another, let the trustee (faithfully) discharge his trust, and let him Fear his Lord and conceal not evidence; for whoever conceals it, - his heart is tainted with sin. And God knoweth all that ye do."
Yusuf Ali's translation.
read the verse within the context of a time when women didn't have much to do with life in general and you'll understand.
not to mention the verse is not general so it can't be taken as an absolute, it specifies the case of writing a loan to payed after a set time, and that case only, thus we can assume quite correctly that women didn't do much trading and loaning at that time hence the ruling, not as some made it that in every case under law a man's worth as a witness equals two women.