The Conditions and Condition blocks can be used to render content when a certain condition applies.
Condition
The ska/condition
block allows to set any PHP function name as as the condition for rendering itself.

For example, using the condition get_locale
and value en_US
allows to render content only when the current language is English.
Conditions
The ska/conditions
block is just a wrapper for ska/condition
blocks, that doesn’t do anything special in the front end, how ever in the block editor it only displays 1 child condition at a time – first condition or the condition that is currently selected in the List view.

This can be used to keep the block editor content more compact, how ever it may be confusing for people who don’t know about this behavior. If you need to disable it, you can add a Tailwind class:
editor:[&>.wp-block:not(#\_):not(#\_):not(#\_)]:!block