Welcome to... "Micro-Lesson 244"
The riff operates with the front end (first two measures) jamming on a couple of Major 6th style triads that can work to cover the sounds of "Bb7 and Ab7" chords. The riff then moves on to a melodic phrase that involves a mix of "Bb Major Pentatonic" with the "Bb Mixolydian" mode. The run is fairly easy to perform and operates mostly within the 5th position of the fingerboard.
The feel throughout is swung (Blues Shuffle-Rhythm) and primarily flows through eighth-note groove with a sixteenth-note triplet applied in the 3rd measure.
Take your time and memorize the chords if they are new to you. Work out all of the fingerings for the melodic line until the entire part is committed to memory. This is especially important if the scales used in this section are foreign to you.
Build the speed with a metronome or a drum machine. The tempo is quite fast with the goal speed set at 132 b.p.m. Enjoy!
Micro Lesson 244: "Bb Blues" Jump-Blues Riff