1. a place which is safe/not dangerous
a safe environment to raise children/to live in
The expression 'a safe environment' can refer to an environment or place that is physically safe (in terms of structure, being free from threats of violence, etc.) It can also mean a space which is a safe space figuratively in terms of sharing experiences or information without consequences: "This environment is a safe space to share any issues you might have with bullying in the workplace." This is a very popular term you will hear used in a number of contexts.