Truly, Allah is with those who have Taqwa, and the doers of good.
meaning; He is with them in the sense of supporting them, helping them and guiding them.
This is a special kind of "being with", as Allah says elsewhere;
إِذْ يُوحِى رَبُّكَ إِلَى الْمَلَـيِكَةِ أَنِّي مَعَكُمْ فَثَبِّتُواْ الَّذِينَ ءَامَنُواْ
(Remember) when your Lord revealed to the angels, "Verily, I am with you, so support those who believe." (8;12)
And Allah said to Musa and Harun;
لَا تَخَافَأ إِنَّنِى مَعَكُمَأ أَسْمَعُ وَأَرَى
Fear not, verily I am with you both, hearing and seeing. (20;46)
The Prophet said to (Abu Bakr) As-Siddiq when they were in the cave;
لَاا تَحْزَنْ إِنَّ اللهَ مَعَنَا
Do not worry, Allah is with us."
The general kind of "being with" some one, or something is by means of seeing, hearing and knowing, as Allah says;
وَهُوَ مَعَكُمْ أَيْنَ مَا كُنتُمْ وَاللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ
And He is with you wherever you may be. And Allah sees whatever you do. (57;4)
أَلَمْ تَرَ أَنَّ اللَّهَ يَعْلَمُ مَا فِى السَّمَـوَتِ وَمَا فِى الاٌّرْضِ مَا يَكُونُ مِن نَّجْوَى ثَلَـثَةٍ إِلاَّ هُوَ رَابِعُهُمْ وَلَا خَمْسَةٍ إِلاَّ هُوَ سَادِسُهُمْ وَلَا أَدْنَى مِن ذَلِكَ وَلَا أَكْثَرَ إِلاَّ هُوَ مَعَهُمْ أَيْنَ مَا كَانُواْ
Have you not seen that Allah knows whatever is in the heavens and whatever is on the earth There is no secret counsel of three but He is their fourth, - nor of five but He is their sixth, - nor of less than that or more, but He is with them wherever they may be. (58;7)
وَمَا تَكُونُ فِى شَأْنٍ وَمَا تَتْلُواْ مِنْهُ مِن قُرْءَانٍ وَلَا تَعْمَلُونَ مِنْ عَمَلٍ إِلاَّ كُنَّا عَلَيْكُمْ شُهُودًا
You will not be in any circumstance, nor recite any portion of the Qur'an, nor having done any deeds, but We are witnessing you. (10;61)
الَّذِينَ اتَّقَواْ
those who have Taqwa,
means, they keep away from that which is forbidden.
وَّالَّذِينَ هُم مُّحْسِنُونَ
and the doers of good.
meaning they do deeds of obedience to Allah. These are the ones whom Allah takes care of, He gives them support, and helps them to prevail over their enemies and opponents.
This is end of the Tafsir of Surah Al-Nahl. To Allah be praise and blessings, and peace and blessings be upon Muhammad and his family and Companions