Welcome to the forum, but your first post and no information offered to help us - sorry -
First, some details about your computer setup and network: 1) Computer(s) - brand/models/years; 2) Brand/model of the printer; 3) How is the printer communicating (e.g. is it wired via USB into another computer or setup wirelessly); 4) Details of your network (e.g. ISP, modem, router brand/model); and 5) What have you done to correct the situation?
Just one postulation - if you are trying to print 'wirelessly' from your MacBook Air and your printer is not AirPrint compatible, then that is the likely explanation - let me stop there so you can provide the details needed for us to help - Dave