en_tn/jhn/02/14.md

were sitting there

The next verse makes it clear that these people are in the temple courtyard. That area was intended for worship and not for commerce.

sellers of oxen and sheep and pigeons

People are buying animals in the temple courtyard to sacrifice them to God.

money changers

Jewish authorities required people who wanted to buy animals for sacrifices to exchange their money for special money from the "money changers."