Hope you're not sick of seeing ads on your Facebook feed.

Facebook Chief Operating Officer Sheryl Sandberg told Reuters on Monday that more than 5 million companies are advertising on its social network each month, up from 4 million that it disclosed in September.

The company's just getting started. Sandberg said that Facebook is updating its suite of ad services to draw in more small businesses.

Facebook and Google are the two giants in the digital ad business, and both are keen in particular on better serving you ads on your phone. Facebook boasts tools like audience targeting, a mobile design studio and online courses.

A Facebook spokesman wasn't immediately available to elaborate on her comments.