“Verily we have sent it down as an Arabic Qur’ân in order that you may understand” [Soorah Yusuf: 2]
“And thus We have inspired unto you (O Muhammad) an Arabic Qur’ân that you may warn the mother of the towns (Makkah) and all around it” [Soorah ash-Shura: 7]
“And truly this (the Qur’ân) is a revelation from the Lord of the ‘Alamin (mankind, jinns and all that exists), which the trustworthy Ruh (Jibreel) has brought down upon your heart (O Muhammad) that you may be (one) of the warners, in the plain Arabic language” [Soorah ash-Shura: 192-195]
Learning Arabic is very important – in order to understand it. Allah says in the Qur’an in Soorah Qamar:
وَلَقَدْ يَسَّرْنَا الْقُرْآنَ لِلذِّكْرِ فَهَلْ مِن مُّدَّكِرٍ
Learn Qur’anic Arabic – http://www.80percentwords.com/
Learn Arabic Online – http://www.learnarabiconline.com/
The Medina Books – http://abdurrahman.org/arabic/madina-arabic.html
And from a lot more places.
Insha’Allah, you will understand the Qur’an.