Bird's is a standard flank opening. White's strategic ideas involve control of the e5-square, offering good attacking chances at the expense of slightly weakening his own kingside. Black may challenge White's plan to control e5 immediately by playing From's Gambit (1...e5); however, the From Gambit is notoriously double-edged and should only be played after significant study.
https://en.wikipedia.org/wiki/Bird%27s_Opening