What that means..?

[ajUmanOj]

[TheFastestIndian]

Every 24 hrs or 4 hrs of phone being Idle for face recognition or 72 hrs for fingerprint you will have to enter your pin or password instead of biometrics

[S_Kumar73]

If you are not using the phone continuously for 4 hours or more then you won't able to unlock with fingerprint sensor or face unlock. You have to unlock with PIN/pattern.

[ajUmanOj]

But now i am unable to register fingerprint, pls tell me how to overcome on this.
Now face recognition & pin was the only option showing to unlock.