Das ist mein Handy.
English: This is my phone.
Demonstratives point to people or things by distance and number. In German, 'dies-' and 'jen-' are used.
Use demonstratives to identify items in context, often with 'sein'.
Das ist mein Handy.
English: This is my phone.
Das ist unser Bus.
English: That is our bus.
Das sind meine Schlüssel.
English: These are my keys.
Das sind deine Schuhe.
English: Those are your shoes.