Unless you have controlled a creature continuously since the beginning of your most recent turn, you cannot attack with or use the ability of that creature that has the tap symbol as part of the cost. This is referred to by the informal term ‘summoning sickness.’ (See here.)

It is important to keep in mind that how long has been in play does not matter, but how long a player has controlled the permanent does. When a permanent changes controllers it ‘resets’ and will not be able to attack or tap to use it’s own activated ability that has the tap symbol. For example, a player that gains control of a creature via Bazaar Trader‘s ability will not be able to attack with it or used it’s own activated ability that has the tap symbol until this player controls the ‘donated’ creature since the beginning of their most recent turn.