It's kind of a contraction but not really. It is like most Indo-European languages there are personal forms of verbs. There were also for the other persons but in modern Irish only the 1st person singular and 1st person plural retain the personal forms, in which case no pronoun is needed. These were replaced by the forms endin in -ann -eann -ionn etc for the other personson on verbs other than ta/is (bheith) This is not possible in English because, even if we maintained the 'thou' form, all the plural forms are the same: am, art, is, are are are. If we say the first three without pronoun we know clearly what person (at least number-wise) the verb refers to. another example is to have (Old-English infinitive = habban): have, hast, hath/has, have, have, have) German conjugation of 'haben': habe, hast, hatt, haben, hat, haben. Here we see that the English lost endings in the plural: ic hæbbe þū hafas/hafast/hæfst, he/heo/hit hafaþ/hæfþ, we habbaþm. ge habbaþ, hio habbaþ (þ = th which corresponds to the t at the end of the other Germanic and Romance languages). And we see even then the plurals are the same in the Old English period. if there ever were different forms for the plurals it had to be during the archaic period
So from what I've gathered so far, being also a beginner at this language (some of this is also in the Tips & Notes section for this skill).
Irish uses the word order of [verb] [subject] [object]. In case you don't know what those are, the verb is the action, the subject is the one doing the action, and the object is what the action is being done to.
There is distinct conjugation in Irish, meaning a different form of a verb based on who is doing it. It's much like the forms we have for "to be" (I AM, he IS, they ARE, you ARE, it IS). Some of the forms have weird exceptions (especially with the form for 'we' and 'I', from what I can tell), like 'táim', which means in and of itself "I am", but it's really in the order "Am I".
So think of sentences like this. "I eat an apple" = "Eat I an apple"
Hope this helps a little! I'm still getting used to it, too.