I have access for the Hindi translation of OpenTTD but I need help translating.

[NisheshTyagi]

I can't seem to figure out how to translate properly. There are various confusing string and I don't know how to properly translate them like:
{BLACK}Build or generate industries
Should I keep the "{BLACK}" part and translate everything else?
What is
"Plural syntax: {P [index] "1" "other" }"?
Is there any documentation to understand how to handle these types of string and what is the syntax of the translations files?
It would help me a lot.

[rubidium42]

There is https://translator.openttd.org/static/docs/strings.html which should explain most.

[NisheshTyagi]

Oh, thanks!