This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of hard? It's hard, firm, or tough.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
You need something really hard to put in your catapult(かた). Look around you for something hard and imagine putting it in your catapult!
This meat is a little tough.
I think my father's decision is firm.
My elder brother is known as someone who can keep a secret.