Jesus continued his ministry in other places, but for now, he did got enter Judea. His reasoning was that at that time, the Jews wanted to kill Jesus. At the same time, the Feast of Tabernacles (AKA an important event) for the Judean community) is around the corner.
However, Jesus's brothers had some questions regarding why Jesus would not go into Judea at that time. They told Jesus that the disciples can see even more works in Judea (7:3). Additionally, they pointed out how one who wants to reveal oneself would not do stuff in secret (7:4). For Jesus's brothers, secrecy for one who wants to reveal oneself is a step backward. Additionally, the writer pointed out how at that time, Jesus's brothers did not believe in Jesus yet (7:5). They want to see signs and feats so they can be convinced of Jesus's reliability.
It's worth noting that one chapter ago (John 6), various Judeans have experience with Jesus's feats and even heard about Jesus's credentials being revealed to them. However, some of the people who saw and heard such things did not believe in Jesus. Thus, signs and feats do not guarantee that people would believe in Jesus. Though keep in mind that the brothers may not have known of such events.