When somebody does hajj and umrah, it is a rukn to do sa’ee, but Allah says “there is no harm” laa junaaha. That word was persian “gunaah” and came to arabic as “junaah”. Before Islam came, there were 2 idols between safaa and marwa, so when the mushrikeen would do sa’ee and do sajdah at each idol. When islam came, some of the companions would avoid where the shirk happens. So this ayah came as reassurance that you can go.
Those who hide the truth, this is indication towards the jews at the time as they hid the signs of prophethood, and so Allah curses them, and all those who curse also curse them. Except the ones who make tawbah, change themselves, and clarify what they used to hide, Allah accepts their tawbah.