The m7(b5) chord, without brackets just m7b5, is also called „half-diminished“ chord. It’s the chord that you get by stacking 3rds on top of the seventh (VII.) degree of a major scale.
The Cm7b5 has the tones C (1), Eb (m3), Gb (b5) and Bb (7). It can be found on the VII. scale degree of the Db major scale.
On the fretboard chord shapes for Cm7b5 can be drived from Cm7 by taking the 5th and placing it one fret lower, turning it into a diminished 5th. Attention: the 5th may occur two times in a shape. You can also omit one of them.
Another Trick: take a Bmaj7 chord shape and move the root B one fret higher to C. Now you have a Cm7(b5).
In comparison with a dim7 chord, which has a diminished 7th (same tone as a major 6th), the half diminished chord has a minor 7th. A Cm7(b5) has a minor 7th Bb (7), while Cdim7 has the diminshed 7th Bbb (dim7) = A (6).
Especially in in jazz, soul and related styles the m7(b5) is very common. It often occurs in the II-V-I progression in minor, for example Cm7(b5) F7(#9) Bbm7 or Cm7(b5) F7(b13) Bbm9.