The accusative case marks the object of the sentence. So in a sentence such as, “I eat rice”, rice will be the कर्म or the object of the sentence.

The accusative suffix marker is को. So the sentence “I eat mango” will be आम को.

When को is attached to a singular masculine noun that ends in आ, the आ will change to an ए. So लड़का (boy) will change to लड़के को, and लड़की (girl) will change to a लड़की को.

When को is attached to any plural noun the suffix ओं is attached to the noun before attaching the को suffix. So it’ll be लड़कों को or लड़कियों को.

When there’s an intransitive action, the को suffix may be dropped. In a sentence like this, मैं दिल्ली जाता हूँ, the को suffix was dropped because “to go” is an instransitive verb. (मैं दिल्ली जाता हूँ = I go to Delhi)

In Hindi, usually when you do something to someone, you’ll use the accusative case. However, for some verbs the suffix से is used in place of को. We’ll look at से in more detail in the next post. For now just remember that कहना (to say) use से instead of को. An example of this is: मैं उससे कहूँगा (I will speak to him).

Here are some more examples:

She was writing a letter – वह पत्र लिख रही  थी

I had gone to Delhi – मैं दिल्ली (को) गया था 

He saw a lion – उस ने  शेर (को) देखा