This is the 224th most frequent Romanian word.
clar
Clear.
In this sentence, "clar" is used as an adjective meaning "clear" or "evident" to describe the word "lucru" (thing).
Este un lucru clar că trebuie să învățăm zilnic.
It is a clear thing that we must study daily.
Here, "clar" is used as an adverb meaning "clearly," indicating the manner in which the subject explained something.
Am explicat clar cum funcționează sistemul.
I explained clearly how the system works.
Here, "clare" is the feminine plural form of the adjective "clar," agreeing with the noun "lucruri" (things) which is feminine plural.