When he recites a verse during prayer he translates the meaning into his language in his mind
Question

                I would recite a verse in prayer and then after that I would say what the verse means in English(to understand), is this permissible?

(sometimes I say it in my heart.) For example, I would recite the first verse of Surah Fatiha, then after this I would say: "All praise is due to Allah, the Cherisher and Sustainer of the Worlds." Is this right, or permissible?.
Praise be to Allah.
      There is nothing wrong with it if you recite a verse of the 
      Qur’aan during your prayer and ponder its meaning in your own language, 
      and say that to yourself as you mentioned in the example. This comes under 
      the heading of pondering and thinking of the meaning. That is on condition 
      that you do not utter it out loud, because the one who is praying is 
      forbidden to speak during the prayer, based on the report narrated by 
      Muslim (537) from Mu‘aawiyah ibn al-Hakam al-Sulmi who said: Whilst I was 
      praying with the Messenger of Allaah (blessings and peace of Allah be upon 
      him), a man among the people sneezed and I said: Yarhamuk Allaah 
      (may Allah have mercy on you). The people glared at me and I said: May my 
      mother be bereft of me! Why are you staring at me? They started striking 
      their hands on their thighs, and when I realized that they were telling me 
      to be quiet, (I felt angry) but I kept quiet. When the Messenger of Allaah 
      (blessings and peace of Allah be upon him) had prayed – may my father and 
      mother be sacrificed for him; by Allaah I have never seen a better teacher 
      or better teachings before or since; he did not rebuke me, hit me or 
      revile me – he said: “This prayer is not the right place for any of the 
      people’s speech, rather it is tasbeeh, takbeer and recitation of Qur’aan,” 
      or words to that effect. 

    And because it is not permissible to recite Qur’aan in any 
    language other than Arabic. See the answer to question no.
    3471. 

    It is permissible in naafil prayers to hold a Mus-haf with a 
    tafseer in the margins or footnotes, and to look at the meaning of what you 
    do not understand. See the answer to question no.
    9505 

    And Allah knows best.