Can you help me to understand, how to translate this mod to my native language?
I mean, i play Bob+Angel (russian localization) and i added MomoTweaks+MSP now.
Bob+Angel is perfectly translated, so now i have mix of english and russian item names :) i want to tidy up everything and be it in russian only :)
can you tell me, what files should i edit? Is there any specific file?

Factorio mods have a locale folder, inside that folder are subfolders for each supported language.
As you can see here(https://github.com/ByteSquire/factorio-mods/blob/main/MoreSciencePacks-for1_1/locale/en/en.cfg) there is only an English one for now.
If you want, you can fork the repo, add a new subfolder probably ru and create and ru.cfg inside.
Copy over the contents of en.cfg and replace all the text on the right hand side of the "=" with the russian translation

thanks for reply, i understood everything, but what does "fork the repo" means?

If you are not familiar with GitHub, that's fine.
If you want, you can still create the Russian localisation and send it to me some other way so I might make it available to other players.

well, i tried to unzip the MSP mod, create subfolder and zipped the folder again, but MSP didnt show up in mod menu in Factorio :D zipping/unzipping is not correct? :)

Did you zip the mod correctly? Factorio is very particular about this, the zip must contain one folder named like the mod and that folder contains the subfolders graphics, locale, prototypes...

Also, if you left the unzipped folder inside the mods folder, you need to remove it or move up the subfolder.
Factorio prioritises folders over zip archives

your mods folder should look like this then:
MoreSciencePacks-for1_1/
mod-list.json
mod-settings.dat
or like this:
MoreSciencePacks-for1_1_0.1.24.zip
mod-list.json
mod-settings.dat