no, it's not a credit card.
According to Wikipedia:
A visa is a document issued by a country giving an individual permission to formally request entrance to the country during a given period of time and for certain purposes and usually stamped or glued inside of a passport, or sometimes issued as separate pieces of paper.Many countries require possession of a valid passport and visa as a condition of entry for foreigners, though there exist exemptions .
Visas are associated with the request for permission to enter (or exit) a country, and are thus, for some countries, distinct from actual formal permission for an alien to enter and remain in the country.