Noisy
Picky
い adjective
You can guess this is an adjective from the い at the end. The meaning for the kanji is noisy, so the adjective version is also noisy.
やかましい is a casual but emphatic way to say someone or something is too noisy. It's often used in Japanese comedy and variety shows, so depending on the situation there can be a playful vibe to it. You can even use it in a figurative way to describe someone who's being overly picky, fussy, or annoying about something particular (they're being "noisy" about insignificant details).
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 the やかま reading with this kanji, so here's a mnemonic to help:
My noisy mom has earned the nickname yak-a-Ma (やかま). She's always yakking about my life choices. "Yakka yakka yakka," Ma says.
「ああ、喧しい！だまれ！」
"Ahh, so loud. Shut up!"
喧しくてワニカニに集中できない。
It's so noisy I can't focus on WaniKani.
あいつは妖怪について喧しく質問してくるのでうざい。
That dude bugs me with so many Yokai related questions, he's so annoying.