Data Packs Icon And Description

reference: 

https://minecraft.fandom.com/wiki/Tutorials/Creating_a_data_pack

 This is your datapack folder

• data (folder)   ---  all your loots, functions, worldgen and more goes here
• pack.mcmeta  --- your description goes here
• pack.png  ---  this is the image for your datapack

Text editor

Any text editor should work. It is recommended that the chosen text editor supports JSON, which is the format used by files of mcmeta extension and most other files in a data pack. Note that most text editors do not recognize mcmeta extension as JSON. Thus, you need to configure the editors manually.

pack.mcmeta content

Open pack.mcmeta in your text editor and paste or type the following:

{
  "pack": {
    "pack_format": 7,
    "description": "TYPE HERE WHATEVER YOU LIKE"
  }
}

Note
This file is written in JSON! This tutorial does not go into specifics about the format now, but be aware about how things are laid out. Be very careful not to forget quotation marks, colons, and curly or square brackets. Make sure to not write trailing commas. Missing one of these can lead to your data pack not working correctly! To check your files you can use a JSON validator, such as the one found on JSONLint.

"pack_format"

The value of "pack_format" tells Minecraft what release the data pack is designed for, and is different for certain versions. The following list shows what versions each value is associated with:

4 for versions 1.13 – 1.14.4
5 for versions 1.15 – 1.16.1
6 for versions 1.16.2 – 1.16.5
7 for versions 1.17 - 1.17.1
8 for versions 1.18+
Note: As more updates are released, values may be changed or added.

"description"

The text following "description" can be any string or a raw JSON text. It will show up when you hover over your data pack in the output from /datapack list and in the data pack UI when creating a world. In pack.mcmeta, it is possible to use the § symbol (see Minecraft Formatting codes) in the description of pack.mcmeta and the data pack name.

You have to add the image separately.