How can I repair a leaking tub spout? It's a Moen brand. It drips like
every second. How can I stop it. Please give me advise. Thank you.

It is most likely that the valve is the culprit. It it is at all old,
simply replace it. The spout, which likely has a diverter for the
shower, is Ok. However, my experience is that they (whole mess) are not
easily repairable. Do the whole thing.