I already post a topic about should I upgrade or replace my E5-475G-56XB and I think its better if I upgrade it.
However, I thought it will be better if I post a specific topic so that others who face same problems as me can easily find their answer.

From the image above, I know that my RAM is an 8GB Dual-channel with 2133MHz.
And when I search for its specs,specifically at
https://memory.net/product/hma41gs6afr8n-tf-sk-hynix-1x-8gb-ddr4-2133-sodimm-pc4-17000p-s-dual-rank-x8-module/. I know that it has CAS Latency of 15(CL15) and it's voltage is 1.2V(DDR4). So that means I need to find another RAM with the same specs as I stated above.
At this point, I'm assuming that is all I need to know.
My question is, other than the information stated above, do I need to consider other factor to upgrade my RAM? Can I use 8GB 1Rx8, or 16GB 2Rx8, or 4GB 1Rx16? Is there anything else I need to know? Can I use other brand RAM with my current RAM? And if decide to switch both of the RAM, does my laptop accept CAS latency other than 15?