إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ
Thee (alone) we worship; and Thee (alone) we ask for help. (al-Fatiha 1: 5)
The most fundamental aspect of Islam is that of Tauhid - the oneness of Allah (swt). Nothing else is as important as this one concept. It thus the main theme of the Quran and this ayah makes an indirect reference to it.
A normal Arabic sentence might be: "Kataba Muhammad al-Darsa" - Muhammad wrote the lesson.
In this sentence the first word is the verb (to write) the second one is the doer (Muhammad) and the last word is the object (the lesson). So in normal Arabic sentence structure the verb comes first and then the object.
But in the ayah above the positions of the two are reversed: the object (Iyyaaka - You) is mentioned first and then the verb (Na'budu - we worship) second. And there is profound wisdom in this subtle difference.
In the normal sentence structure; it is possible to add on more objects after the first. For example one could say: 'We worship the Father and the Son and the Holy Ghost.' [notice that these objects came after the words; 'We Worship...']
But when the Object is placed first before the action/verb, all attention is payed to that alone and nothing else. That is why the translation is given as "Thee (alone) do we worship" even though the word "alone" is nowhere mentioned in the Arabic of the ayah/verse.
So even the phrasing of the sentence has an effect on the meaning and it is here an allusion to the supreme Oneness of Allah, and the worship of Him alone.