Bottle means courage or nerve. If you’ve got bottle, you’ll actually crack on and do the scary thing. If you bottle it, you freeze up and back out right at the last second. It’s linked to Cockney rhyming slang, where bottle and glass means arse, so losing your bottle is losing your nerve. Very UK, very relatable.
"He swore he’d ask for a pay rise, walked into the boss’s office, then bottled it and started chatting about the weather instead."