What is this symbol circled in green in the image? Is related to that induction motor, and I guess it is a french project (if that helps).
The capacitor symbol inside it may be a clue; the block next to it is one way of representing a resistor, and the staggered lines above it suggest there are three.
Given this, I suspect it's three R-C snubbers, wired in delta, to reduce noise and switching transients on the 3 phase supply. This IS a guess, but there's not much else it could be.
Component values? Resistors in the tens of ohms, capacitors a fraction of a microfarad (e.g. 47R,0.1uF) would be typical. The physical unit is probably a sealed metal can, and may or may not have such useful information printed on it.
Given that it is on a 3 phase motor, I'd say it is a set of Power factor Correction capacitors, which typically come with discharge resistors. The graphic is likely a lazy way of depicting it, this is the more complete version:
Or the image is a copy of a copy of a copy, and some of the lines have been lost.
My guess would be that the box is perhaps referring to another sheet that might have a schematic for that box, referenced with the Z2K that's by it. But, I can't be certain because I don't recall that kind of box and reference scheme including any symbols inside the box, usually.