Reusable blocks are an excellent way to speed up content creation in the WordPress framework. If you create a block you can save it from the menu using the three vertical dots at the top of the block (block options), give the block a name and save the block. If you click on the plus sign at the bottom of the post and then click “Reusable” and then select the reusable block. Now you can use that block anywhere on your WordPress website.
If you want to edit the reusable block, you have a couple of options:
Option one, you can click the edit button above the block and perform an edit. NOTE: it will edit all blocks with that name on your website.
Option two, you can click the options menu and remove that block from being a reusable block, and edit as normal. Reusable blocks will save all of the formattings also for that block, so all of the block colors and backgrounds will be saved as well.
How do I Work With Reusable Blocks in WordPress?
How do I Work With Reusable Blocks in the New Version of WordPress?