Coming immediately after the present one.

अगले

English Usage: I will see you at my next appointment.

Hindi Usage: मैं आपको अपनी अगली नियुक्ति पर देखूंगा।

The one that follows in order or time.

अगला

English Usage: The next train will arrive at 5 PM.

Hindi Usage: अग्ली ट्रेन शाम 5 बजे पहुंचेगी।

Immediately afterward.

तुरंत बाद

English Usage: Please go to the next room.

Hindi Usage: कृपया अगले कमरे में जाएं।

In relation to the person or thing mentioned.

संबंध में

English Usage: He sat next to me during the meeting.

Hindi Usage: वह बैठक के दौरान मेरे पास बैठा।