Transferable visa
A residence visa that can be moved to a new sponsor without the holder leaving the country.
When a helper's visa is described as transferable, it means the sponsorship can in principle be moved to you while she remains in the UAE — no exit, no re-entry, and a much shorter gap before she can start.
"In principle" is doing real work in that sentence. Transferability depends on her current sponsor releasing her, on her contract status, and on current immigration rules, which change. A Tadbeer centre will tell you what is actually possible in a given case.
Why it matters
Transferable is faster and cheaper than overseas recruitment, but it is not automatic. Confirm it with the licensed centre before you plan around a start date.
See also
This is general information, not legal advice, and the rules change. Confirm anything you intend to act on with a licensed Tadbeer centre or with MOHRE.