Starting at Bb, these are Major, Minor and 7th Barre Chords. Use your Index (1) finger to form the "bar." Once you learn these chords, you can slide the entire fixed fingering pattern up the neck to form a new chord on each fret.
For example, the lowest Major barre chord based on A is Bb Major. Slide that fixed pattern up the next fret and you have a B Major (See: Sharps and Flats). Slide up another fret and you get a C Major chord. Make sure you don’t play the low E string. You can use either your thumb or the tip of your index (1) finger to mute the low E string n case you accidentally strum that string.