It implies that something is currently planned but may need to be adjusted or cancelled depending on further developments.
Examples:
* "Our meeting is tentative as of now, but we'll confirm the time and date later."
* "The release date of the new album is tentative, so don't be surprised if it gets pushed back."
* "The travel plans are tentative due to the ongoing pandemic."
Essentially, it means "for now, this is the plan, but things could change".