Sports betting picks are plays and suggestions for certain events, often sold by a tout or handicapper.
Similar to how everyone can be a sports betting handicapper, everyone can give sports betting picks.
For example, your friend could tell you to bet the Tampa Bay Bucs +180 moneyline against the New Orleans Saints and that is considered a pick. However, when you see sports betting picks online, it usually refers to someone selling their plays. More specifically, professional handicappers and touts will often sell their picks because they are "experts" and have secret information to the matchup.
There are some sites that give free picks as an introduction of what they provide or because they want to do it for fun. While picks are nice, it's usually best to use them only if stats and information is given, as well.
Referring to the above example, why is your friend betting the Bucs as an underdog? Do they play better as an underdog? Is someone hurt on the Saints? Do the Bucs match up well?
Otherwise, anyone on the internet can sell you sports betting picks and tell you they are hitting at an unbelievable 80% rate without giving any information backing up their selections. Sports betting picks can be useful if you need something to back up your original thoughts, but without research, anyone can give a side and sell a pick to a game without knowing anything about the matchup.
As always, be wary of sports betting touts who sell their picks online for a profit. If they were a successful bettor, they wouldn't need to sell picks.