请自便 means "please do as you please" or "please make yourself at home" in English. This phrase comes from the idea of granting someone the freedom to act or do as they wish, without constraints or limitations.

For example, you could say "请自便，这里是您的家" which means "Please make yourself at home, this is your home."

Another example would be "请自便，随便坐" which means "Please do as you please, sit wherever you like."