It will take a while to "get your head around" the concepts.
As others say, html is a text formatting language not a programming language.
A Variable is a "chunk" of storage you give a name to; think of it like a pigeonhole or a line on a notepad.
You can store a number or bit of text in it & when you use that name on your program, the content are automatically used instead.
It's a bit like using a letter to represent an unknown in maths, like 3x + 1; you can put any number you like in the variable called x and get a different result from the same calculation.
That's what a lot of programming is based around, writing a fixed routing that does something with a combination of variables.
By setting them to different values before running that routine, you get different results.
It could eg. be to do a math or trig calculation or to count the letters in a word.
Why Python? - It's presently what someone decided was a good teaching language.
That does not mean it's easy... Some year back, schools changed from BASIC (a really easy and forgiving language) to PASCAL - specifically because that is much harder and will not tolerate the slightest error.
(That's now pretty much forgotten in mainstream programming as well...)
The simplest language of all is possibly the one used in Livecode. That's a program for creating mobile apps and general programs. It's language "Revolution" is very similar to plain english.
It's also completely different from any conventional programming language - but does give you an idea of the concepts and is very easy to use.
https://livecode.com/
The single most useful "mainstream" programming language is "C" - it's used for programming everything from little single-chip microcontrollers through phones, tablets, laptops, PCs, servers and up to Supercomputers.
It's not the easiest language to learn, but it has a lot of similarities with both Java and PHP, so you get a head start with those, if you ever want to use them.
There are probably more tutorials for that than any other language and many online resources.