Turn verbs into nouns and master the こと family, including when こと and の are interchangeable and when they are not.
〜こと (nominalizer) V-dict / V-nai + こと
Verb (dictionary form) + こと turns a verb into a noun phrase, like '-ing' or 'to do' in English. Used for general activities, facts, and abstract ideas.
私の趣味は音楽を聞くことです。 My hobby is listening to music.
〜の (nominalizer) V-plain + の
Verb (plain form) + の turns a verb into a noun phrase. Often used with verbs of perception and feeling (見る, 聞く, 好き, 忘れる) and for concrete actions.
彼が歌うのを聞きました。 I heard him sing.
〜ことができる V-dict + ことができる
Verb (dictionary form) + ことができる. Expresses ability or possibility: 'can, be able to'. Slightly more formal than the potential form.
妹はピアノを弾くことができます。 My little sister can play the piano.
〜ことがある V-dict / V-nai + ことがある
Verb (dictionary form) + ことがある. Expresses that something happens occasionally or sometimes.
週末は遅くまで寝ることがある。 On weekends I sometimes sleep in late.