i just switched from windows to linux, so how to step by step install the missing fonts?
RE: LibreELEC (Leia) 9.2.5
------
X Chrome and Firefox display text based on availability of fonts in X windows. If you don't have some language specific code pages across all installed fonts, text is displayed as boxes.
Create .fonts directory in /storage (root user's home) and copy any ttf fonts that you want to that directory. Reboot to restart X windows to be on safe side. I did not check if X detected changes in fonts without restart.
DejaVu fonts will show Arabic in Chrome. Chinese, Japanese and Korean will require more fonts. Next fonts of choice would be non free MS core fonts, Tahoma, Arial Unicode MS and SimSun. SimSun will give Japanese and Chinese.
------
If you still have Windows with Chinese support, you probably got SimSun font in there or Arial Unicode MS. Any other TrueType or OpenType font that can display Chinese will do too. I can't recommend Chinese fonts by name as I am not Chinese and my Chinese font support normally comes from font packages supplied by Linux Debian. My international font knowledge is only slightly newer than that geosites page and I might be unaware about latest free developments in Chinese fonts.
If you are not familiar with Linux CLI, LibreElec got system-tools addon package that has mc utility. It will give you GUI and it will come down to creating directory with F7 and copying files from USB flash drive to that directory. USB flash drive should be visible in /var/media directory once you attach it to libreelec pc.