Grammar Point
particle
prt 
が

indicates sentence subject (occasionally object)

Subject Marker

The particle が is used to mark the subject of a sentence, specifically identifying who or what performs an action or exists in a state. It is often used when introducing new information or when the subject needs to be specifically identified among other possibilities.

Noun + が

Used with nouns to indicate that the noun is the one performing the action or exists in the described state.

Rain is falling.

The cat is here.

Note

While は is used to mark the topic of a sentence (what the sentence is about), が is used to mark the grammatical subject. In many cases, が is used to introduce a subject for the first time in a conversation. Additionally, some verbs and adjectives related to ability, desire, or perception (like わかる, ほしい, or すき) use が to mark the object of the emotion or state rather than the direct object particle を.

Words: 
が
Radicals of radicals