What is the meaning of Og?

Initialism of own goal.

indefinite indirect marker for nouns other than personal names.

refers to motion towards an indefinite location:

refers to accompaniment with an indefinite partner or object: with a

refers to an indefinite tool or instrument used for doing: with, through, by

shows relation between two grammatical parts:

1. preceding infinitives

   preceding infinitives

   with adjectives of manner

   after ayaw (“don't”)

   having, possessing as an attribute:

   and

   also

   and

   water

   and

   and

   egg

   testicle

   and

   romanization of 𐍉𐌲

   and

   harrow

   Source: wiktionary.org