3 text ads, 3 link ads, and aside from that you can have a search box as well. its not how many you can put, its how well you can adsnse optimize your page. sometimes having less ads can make you more. more ads you have, lower the payout is for bottom ads so when people clicks on the bottom ads, you get paid less. top ads always pay more so try to add less ads but optimize properly so that people click on the higher paying ads.