وَلَقَدْ جَاءكُم مُّوسَى بِالْبَيِّنَاتِ
 
 

And indeed Musa came to you with clear proofs,

meaning, with clear signs and clear proofs that he was the Messenger of Allah and that there is no deity worthy of worship except Allah.

The clear signs -or miracles- mentioned here are; 

the flood, 

the locusts, 

the lice, 

the frogs, 

the blood, 

the staff and 

the hand. 

Musa's miracles also include; 

parting the sea, 

shading the Jews with clouds, 

the <b>manna</b> and quails, 

the gushing stone, etc. 
 
ثُمَّ اتَّخَذْتُمُ الْعِجْلَ

yet you worshipped the calf,

meaning, as a deity instead of Allah, during the time of Musa.

Allah's statement,
 
مِن بَعْدِهِ

after he left,

after Musa went to Mount Tur to speak to Allah.

Similarly, Allah said,

وَاتَّخَذَ قَوْمُ مُوسَى مِن بَعْدِهِ مِنْ حُلِيِّهِمْ عِجْلً جَسَداً لَّهُ خُوَارٌ

And the people of Musa made in his absence, out of their ornaments, the image of a calf (for worship). It had a sound (as if it was mooing). (7:148)
 
وَأَنتُمْ ظَالِمُونَ
 
 

and you were <b>Zalimun</b>.

meaning, you were unjust in this behavior of worshipping the calf, although you knew that there is no deity worthy of worship except Allah.

Similarly, Allah said,

وَلَمَّا سُقِطَ فَى أَيْدِيهِمْ وَرَأَوْاْ أَنَّهُمْ قَدْ ضَلُّواْ قَالُواْ لَيِن لَّمْ يَرْحَمْنَا رَبُّنَا وَيَغْفِرْ لَنَا لَنَكُونَنَّ مِنَ الْخَـسِرِينَ


And when they regretted and saw that they had gone astray, they (repented and) said:"If our Lord have not mercy upon us and forgive us, we shall certainly be of the losers." (7:149