Instead of repeating the same noun over and over ('I see the book. I read the book. I like the book.'), we use pronouns ('I see it. I read it.'). This makes your Spanish sound much more fluid and natural.
Direct object pronouns replace the 'what' or 'who' receiving the action. The tricky part for English speakers is that in Spanish, these pronouns usually go BEFORE the conjugated verb, not after!
The biggest pitfall is word order. English speakers naturally want to say 'Yo tengo lo' (I have it), but Spanish requires the pronoun before the verb: 'Yo lo tengo'. Also, remember to match the gender and number of the noun you are replacing!
Choose the correct pronoun and placement to replace the highlighted noun.
Test your object pronoun skills!
While pronouns normally go before a conjugated verb, they can be ATTACHED to the end of an infinitive verb (e.g., 'Quiero comerlo' - I want to eat it) or a gerund (e.g., 'Estoy comiéndolo' - I am eating it).