Some translations set poetry farther to the right than the rest of the text to show that it is poetry. The ULB does this with the poetry in 15:8-9, which is from the Old Testament.
The "traditions of the elders" were oral laws that the Jewish religious leaders developed because they wanted to make sure that everyone obeyed the law of Moses. However, they often worked harder to obey these rules than to obey the law of Moses itself. Jesus rebuked the religious leaders for this, and they became angry as a result. (See: [[rc://en/tw/dict/bible/kt/lawofmoses]])
The Jews of Jesus's time thought that only Jews could please God by the way they lived. Jesus healed a Canaanite Gentile woman's daughter to show his followers that he would accept both Jews and Gentiles as his people.
The Bible often speaks of people as if they were sheep because sheep need someone to take care of them. This is because they do not see well and they often go to where other animals can kill them easily. (See: [[rc://en/ta/man/jit/figs-metaphor]])