Cheat Engine

[Meas]

I'm not well versed in assembler terminology but I'd say it's the base address of the player struct.

In this case ECX will be the address of the player struct and ECX+E2 gives you the pointer to the HP value. The brackets, [ECX+E2], will dereference the pointer which means: read the value that is stored at the address ECX+OFFSET.

Note that there's no guarantee that the ECX register at that instruction will always point to the player address. There might be multiple structs in the game you're hacking that all pass through that same instruction. You can right-click the instruction in CE and "Find out what addresses this instruction accesses" to see this.