What do you mean by computer Assembly?

This can mean one of two different things depending on context. The obvious one is the physical assembly of a computer, but since you're asking here, I assume you're asking about assembly language.

The CPU inside your computer can only understand a limited set of relatively simple instructions. These instructions are represented by numbers, and the CPU knows which number means which instruction. Assembly language is a human readable representation of the instructions that the CPU can understand. Instead of a large number, a short Word or acronym called a mnemonic is used. When an assembly program is written, a program called an assembler can translate each mnemonic into the number that represents it. Each mnemonic corresponds to one instruction that the CPU will follow.