Most people have heard the word "bloatware" and if you haven't, then you probably still know what it is.
When you get a brand new phone and there are already apps on it... That's bloatware. Some of these apps on your phone may be part of Android (The Play Store etc), but some aren't vital.
Bloat, as in unneeded or unwanted stuff. Ware, like software etc.
Some things you may not think of as bloat, or not mind as you use it anyway. Other things may be annoying; extra icons that you don't want, extra things running that slow down your phone and use up memory.
I think, at least on android phones, that the situation has got better. And, in fact, maybe you can lose some of the bloat and didn't realise that you could.
Your phone has "storage", not to be mixed up with memory. It is like a computer hard disk. It might be 8Gb, 64Gb or even more. It, generally, has two areas. The phone manufacturer will have partitioned it to have an area for Android along with it's built-in apps (including bloat) and an area for apps you want and the data they store. I'll call these the "system" and the "user" area.
The system area is mostly off-limits to you. Android lives there and, if they are still supporting your phone, system updates will be put there. Which means, even though your system update is a few hundred megabytes (or more), it won't use up any user area.
The user area is for you. You download Angry Birds, and it starts to fill up. But some of the system apps, not android itself, and the bloat apps will want to update themselves. They can't use the system area. So they download and use up some of your user area. Android knows to use the updated one rather than the old version that is still in the system area.
Fortunately newer android versions have a disable feature! If i press and hold the icon, there is an "app info" option. If it's an app that can't be uninstalled, there hopefully will be a "disable" option!
It will remove the app icon and remove any updates from the user area. It can't remove the initial version, but it will be on the system area and not be using up any app space.