Cores: Each CPU core can execute a set of instructions. The more cores the CPU has, the more simaltanous intructiuons your PC can execute at at the same time

Threads: Cores on a CPU can be virtually split to process even more instructions (hyper threading).

Clock Speed: The higher the clock speed, the faster the CPU can process instructions. CPUs usually have 2 speeds as their clock speeds can throttle, so it can be slower when the PC is idle to save energy.

Memory Type: DDR4 or DDR5? DDR5 supports a higher frequency and therefore higher speed.

Speed: Measured in MHz, it is the amount of the times the ram can read/werite in a second. 

Size: A basic answer is the Sim Racing games wont use more than 16GB, but if you are running other applications as well (streaming, dashboards, etc) 32GB is safer and faster.

80+ Ratings: 80+ is a certification that power supply achieves at least 80% effeciaency under different loads (e.g. without loosing power due to heat or other).

Capacitors:Japanese capacitors are the best. 

Bronze through Platinum: Each higher level denotes of a higher level of power efficiency.