The validity of visa indicates the time limit within which the holder can enter Bangladesh. It is not the duration of stay which is separately mentioned in your visa. Depending on the number of entries, there are three types of visas:

SINGLE ENTRY: Allows a visitor to enter Bangladesh once during the period a visa is valid

DOUBLE ENTRY: Allows a visitor to enter Bangladesh only twice during the period a visa is valid.

MULTIPLE ENTRY: Allows a visitor to enter Bangladesh several times during the period a visa is valid.