The mainstream teaching is that it allows a husband to hit his wife as a last resort in specific circumstances. Some have argued that this means it sanctions domestic violence against women.
The first and perhaps most important point to mention is that this view is based only upon the use of one word in Surah 4, verse 34 of The Quran shown below:
Surah 4 Verse 34
Literal – Word by word
[The] men (are) protectors of the women because Allah (has) bestowed some of them over others and because they spend from their wealth. So, the righteous women (are) obedient, guarding in the unseen that which Allah (orders) them to guard. And those (from) whom you fear their ill-conduct then advise them and forsake them in the bed and set forth to Then if they obey you then (do) not seek against them away. Indeed, Allah is Most High, Most Great.
Surah 4 Verse 35
Literal – Word by word And if you fear dissension between (the) two of then send an arbitrator from his family and an arbitrator from her family. If they both wish reconciliation, Allah will cause reconciliation between both of them. Indeed, Allah is All-Knower, All-Aware.
The Arabic word ‘idriboo’ is commonly translated as hit/beat/strike, however, the flaws with this understanding are as follows:
Some Points to Note
The evidence from The Quran suggests the correct meaning of the word, in this case, would be "cite" or "indicate" them to the authority, hence authority involvement in Surah 4 Verse 35. This also fits in with its usage elsewhere with direct objects.
Please verify everything you have read with the Quran.
Peace and Respect!