Formal:
* "A gaf i helpu?" (ah gahv ee help-oo?) This is the most literal translation and is appropriate for formal situations.
* "Ydw i'n gallu helpu?" (eeth-doo ee'n gal-loo help-oo?) This means "Can I help?" and is also polite.
Informal:
* "Help i ti?" (help ee tee?) This means "Help you?" and is a casual way to offer assistance.
* "Ai oes angen help?" (ah oyse angen help?) This means "Do you need help?" and is a more direct approach.
Specific situations:
* "Oes angen rhywbeth arnat?" (oyse angen rhywbeth ar-nat?) This means "Do you need anything?" and is useful when offering help with something specific.
* "Gallaf i wneud hynny i ti?" (gal-laff ee wneud hyn-nee ee tee?) This means "Can I do that for you?" and is good for offering assistance with a particular task.
The best choice will depend on the situation and your relationship with the person you are talking to.