Isolation is the I in ACID, and it describes how an application protect itself from concurrency problems (race conditions)
Nothing exists in isolation, what affects one country affects everyone. We have to work together to find answers to the enormous challenges that threaten global health, our environment and our world.
In complete isolation, no other users will modify your data. This is equivalent in a concurrent environment to the serializable isolation level.
Other level of isolation are available in a concurrent environment. See Transaction - Isolation (Level|Degree) - (Locking Level ?)