Open the world you want to get the seed from
Pause the game
Open Settings
Go to Game
Find the Seed field
Copy the seed value shown there
If you are in Java Edition, use the command `/seed` if cheats are enabled
If you are in a multiplayer world, ask the server owner for the seed
If you are in Bedrock Edition, check the world settings for the seed
If you are in a realm or server, use server permissions or admin tools if available