Learn Hafestra

Wa is equivalent to is when first meeting someone.
Es is equivalent to is when you've known someone.

Sonwa is equivalent to are when first meeting someone.
Sont is equivalent to are when you've known someone.

In practice, it is considered polite to use Wa or Sonwa, unless you really know someone. Some example sentences:

Je avotte imasu un orenji: I want an orange.
Je amovo oirterru un orenji: I have an orange.

Je avotte imasu un banane: I want an banana.
Je amovo oirterru un banane: I have an banana.