To Hold Something Down, To Grasp Something
transitive verb, ichidan verb
The kanji means push, and this verb means things like to hold something down and to grasp something. This verb is pretty versatile, and you can use it if you're holding down a piece of paper, holding a cloth to a wound, or grasping a concept.
おさえる
This has the same reading as the kanji you learned, so hopefully you can read this on your own.
宇宙人は左手でガッと男の頭を押さえた。
The alien held down the man's head forcefully with his left hand.
この単語は大事なので、しっかり押さえておきましょう!
These words are important, so make sure to master them!
どうしたの、お腹押さえて。
What's wrong? You're holding your stomach.