a small metal device used to lock or unlock something

something that is critical or essential

महत्वपूर्ण चीज

English Usage: Trust is the key to a strong relationship.

Hindi Usage: विश्वास एक मजबूत रिश्ते की महत्वपूर्ण चीज है।

to provide or secure access

पहुँच प्रदान करना

English Usage: You need to key in your password to access the system.

Hindi Usage: आपको सिस्टम तक पहुँचने के लिए अपना पासवर्ड डालना होगा।