To Begin
Something Begins, To Start, Something Starts
intransitive verb, godan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means start, and this verb means to begin or to start. 始まる is the intransitive version, so it doesn't take a direct object. A war begins, for example, or the new school term starts. No direct object, right?
Verbs ending in okurigana that rhyme with ある tend to be intransitive like this. You can remember this because if something is ある, it's just there, existing, not acting on anything else. That's why verbs that sound like it are often intransitive too!
Since this word has okurigana (hiragana attached to the kanji) you know that it's probably going to be the kun'yomi reading.
Lucky for you, the kanji readings for transitive and intransitive verbs are almost always the same. Once you learn one, you know them both! This reading is the same as 始める.
夏休みはいつから始まりますか？
When will summer vacation start?
走って！コンサートが始まっちゃうよ！
Run! The concert is starting!
三時になると、おやつの時間が始まる。
Snack time begins at three o'clock.