The verse is talking about the Jews who conceal Allah’s revelations.
(الْبَيِّنَاتِ ) (Clear proofs): Meaning clear verses and signs which prove Allah’s (swt) unity, the true authenticity of the Messenger Muhammad’s (saws) and his guidance of humanity.
(مِن بَعْدِ مَا بَيَّنَّاهُ لِلنَّاسِ فِي الْكِتَابِ ) (after We made it clear for the people in the Scripture): That is to mean, in the Qur’an.
(أُولَٰئِكَ يَلْعَنُهُمُ اللَّهُ وَيَلْعَنُهُمُ اللَّاعِنُونَ ) (– those are cursed by Allah and cursed by those who curse.): Cursing means to be expelled from Allah’s (swt) mercy. Allah (swt) curses them, and all the creations of Allah (swt) who suffer from them curse them as well. For example, if people in a village abused and disobeyed their Lord then Allah (swt) prevents the rain from falling on them as a punishment, consequently, the plants are damaged so they curse them, the trees are damaged so they curse them, and the animals get hurt so they curse them …
And those who hide what Allah (swt) revealed are cursed by all who are injured of their tyranny, ingratitude and their concealment of what Allah (swt) revealed.