Potential form

The potential form says what someone can do: 漢字が読める, "I can read kanji"; 明日は来られますか, "can you come tomorrow?"

• godan verbs move the last kana to the e-row and add る: 書く → 書ける, 話す → 話せる, 行く → 行ける
• ichidan verbs swap る for られる: 食べる → 食べられる, 見る → 見られる
• する becomes できる, and 来る becomes 来られる (こられる)

The result is itself an ichidan verb, so it conjugates as one: 書けない, 書けます, 書けた.

The object usually switches from を to が: 日本語が話せます. を is also heard, especially in longer sentences.

In casual speech, ichidan verbs often drop the ら: 食べれる, 見れる. It's everywhere in conversation but still counted as non-standard, so here it's a near miss.