obcym

In a sentence

• Nie ufam obcym ludziom.

  I don't trust strangers.

  The word 'obcym' pertains to 'foreign' or 'unknown', here describing people unfamiliar to the speaker.

• Ten język jest mi całkowicie obcym.

  This language is completely foreign to me.

  'Obcym' refers to something not familiar or native; in this case, a language unfamiliar to the speaker.

• Często marzę o podróżach do obcych krajów.

  I often dream of traveling to foreign countries.

  Here, 'obcych' (the plural form) describes countries that are unfamiliar or distant to the speaker.