Do you think that you will enter Paradise before Allah knows (tests) those of you who will perform Jihad and (also) knows (tests) those who are the patient!
The Ayah asks, do you think that you will enter Paradise without being tested with warfare and hardships. Allah said in Surah Al-Baqarah,
أَمْ حَسِبْتُمْ أَن تَدْخُلُواْ الْجَنَّةَ وَلَمَّا يَأْتِكُم مَّثَلُ الَّذِينَ خَلَوْاْ مِن قَبْلِكُم مَّسَّتْهُمُ الْبَأْسَأءُ وَالضَّرَّاءُ وَزُلْزِلُواْ
Or think you that you will enter Paradise without such (trials) as came to those who passed away before you! They were afflicted with severe poverty and ailments and were so shaken... (2:214)
Allah said,
أَحَسِبَ النَّاسُ أَن يُتْرَكُوا أَن يَقُولُوا امَنَّا وَهُمْ لاَ يُفْتَنُونَ
Do people think that they will be left alone because they say: "We believe," and will not be tested. (29:2)
This is why He said here,
أَمْ حَسِبْتُمْ أَن تَدْخُلُواْ الْجَنَّةَ وَلَمَّا يَعْلَمِ اللّهُ الَّذِينَ جَاهَدُواْ مِنكُمْ وَيَعْلَمَ الصَّابِرِينَ
(Do you think that you will enter Paradise before Allah knows (tests) those of you who will perform Jihad and (also) knows (tests) those who are the patient),
meaning, you will not earn Paradise until you are tested and thus Allah knows who among you are the ones who struggle and fight in His cause and are patient in the face of the enemy.
Allah said,
وَلَقَدْ كُنتُمْ تَمَنَّوْنَ الْمَوْتَ مِن قَبْلِ أَن تَلْقَوْهُ فَقَدْ رَأَيْتُمُوهُ وَأَنتُمْ تَنظُرُونَ