开 kāi
Quick Deconstruction:
開：It is the traditional form of “开”. Nowadys, we have simplified the process of writing 開 into 开.
As you can see, 開 has two same parts on both sides, which is 門(the traditional form of 门, door). Okay, you guys have known about this, then it’s easy to understand the following parts.
Inside the word 開, you can see a 开. From this simplified word, imagining that both of your hands are holding a door bolt (the line in the middle) which closes the door, you unlock the door bolt and open the door (that is 門 or 门).
But what does the 門 look like?
From the picture below, you can see two walls standing on the both sides of the main door. They are the two upright lines of 門. As for the main door, you can imagine the cubes on the top of 門 is it.
You hold the door bolt，unlock it，nudge the door，then go inside.
你握住门闩，解开它，推开门，然后走了进去。
Nǐ wò zhù mén shuān, jiě kāi tā, tuī kāi mén, rán hòu zǒu le jìn qù。
Well, you see that I use 门 and 开 instead of 門 and 開, because both of them are the simplified ones so that we can save more time when we write 門 and 開.
开, this word is used reallyyyy common in daily life. The core meaning of it is “Open”, with a feeling of “start (doing)”. From this, we expand a lot of abstract meanings.
For example:
1. 推开：nudge. Often used to mean “open a door softly” like 推开门.
2. 开发：develop.
我们开发了一个软件。
We developed a software.
3. 开始：start.
我们开始开发一个游戏。
We start developing a game.
4. 开心: happy
我一点也不开心。
I am not happy at all.
(一点也不, at all)
5. 开灯: Turn on the light.
6. Set up or found:
for example: 开店(start business)，开公司(start a company)
7. 开花: come into bloom.
"你握住门闩，解开它"
This sounds really weird. I can see you 解开 a knot, or even a lock, but I would never say 解开门闩. It doesn't sound very natural.
I thought this one meant to drive as well?