A flam is term used to describe two notes played shortly after each other (almost simultaneously but not quite).
It is usually used to embellish a part of the song, as it creates a slight accent in the music. On the jembe it is played with two hands, one hitting the drum slightly before the other. It can start with either the leading or following hand and is usually two tones, two slaps or two bass notes, but all other combinations work (e.g. one bass and one slap, one tone one slap, etc).
The easiest is probably two tones, so start there, using either hand to start. Play the first note just before the beat and the second on the beat. When you get the hang of it experiment with slap flams and bass flams.
The symbols for flams on the bass tone and slap are shown below, as well as the words that replace ‘Gun Dun Go Do Pa Ta’:
Each symbol shows two notes, and the words used sound like a flam.
Next, you’re ready for a challenge: Lesson 9 – Paradiddles