My husband had cataracts removed and multifocal lens put in the right eye has shifted now he has to have it fixed is that common and what does it envovle?

Lens shifting. This is not a common problem if the surgery was performed correctly and no complications occurred. Correcting the lens shift should not take long although the lens may need to be sutured and a vitrectomy may be required.
Not common result. This is a difficult question to answer without the benefit of an exam. It is unusual for an implant to move. Repair can range from a simple repositioning to a major surgical intervention with an accompanying high risk. If the capsule had ruptured the procedure is riskier. You and your husband should discuss the cause, intended procedure for repair, and the risks. Good luck.
Shifted lens implant. It is not common to have to re-position lens implants, but a person may more visually sensitive (more visual side effects) to a decentered multifocal lens implant than a decentered traditional implant. However, if there was a complication with the surgery, there are cases where it can be difficult to use some multifocal lenses, and a traditional implant might have to be exchanged in its place.
Multifocal IOL risks. MIOLs have many advantages (more info: eyedoc2020.blogspot.com) Biggest risks aside from general surgery risks.: Halos, glare (usually improves with time), need for reading glasses/distance Rx from residual astigmatism. Rarely (