Translation:I put flowers in the vase.
This is part of the problem, Duolingo. You need to start using the kanji. Why? On-yomi and Kun-yomi. Each kanji has at least two readings, a fact which most but not all of us users have learned by now.
花 = はな 花火 = はなび (firework) 花瓶 = かびん
"Hana" is a meaning-based reading (Kun-yomi). "Ka" is a sound-based, phonetic reading (On-yomi).
So, if you're another learner reading this, you might be thinking, "Ok, so what's the big deal, nerd? Why does that upset you?"
It upsets me because the か reading for the 花 in 花瓶 would normally ONLY be used in a compound word with two or more kanji. Now, these rules may vary in certain exceptional cases, but my basic problem with this is that many of the beginners in this course have no idea what the second kanji would be, nor why the pronunciation of the first kanji changed at all.
TL;DR: This is putting you at a severe disadvantage if you don't already know the rules for kanji. Please, go learn these rules, because Duo is not going to teach you them.
入れる(いれる) is used with an object (in other words it's transitive), it means "to put"
入る(はいる) is used without an object (in other words it's intransitive), it means "to enter"
Japanese actually has quite a lot of these transitive/intransitive verb pairs, I'd recommend reading about it elsewhere at this point, since I don't think duo provides an explanation of this.
The Japanese in Duolingo is okay, but two things I noticed: 1) Lack of kanji and explanation of all the readings 2) This is all proper Japanese, which is great to know but you don't use this for daily conversation (especially when you're younger, there's a lot of slang used) so maybe it'd be nice to add some of that to the final version so people heading to Japan can sound more natural 3) More casual convo practice (敬語はいいんだけど友達と話したらあんま使ってないのでですますなしの練習をもっと入れた方がいいと思います) -From a foreigner living in Japan
It is actually saying "kabin" (かびん, 花びん, 花瓶, however you want to spell it). 花 changes pronunciation from "hana" (はな) to "ka" (か) when in compound words. This happens all over Japanese: when the kanji is by itself, you pronounce it with the kun'yomi (訓読み, in this case はな); if there are more than one, you pronounce it with the on'yomi (音読み, in this case か). There are some exceptions, like always, such as 花火 (firework) pronounced はなび, with the kun'yomi. I hope that this comment helps you understand better why you heard it differently.