Bodhisattva Way Of Life - Homage

Next is the homage, this is a classification system ordered by the Tibetan king Ralpachen long time ago, a way to define the classification of the text that is translated or composed. This text belongs to the sutra basket (sutra-pitaka) so the homage is to Buddhas and bodhisattvas. The reason is that Buddha taught sutra as a question and answer session with bodhisattvas!

The other reason writers pay homage in the beginning is to ensure that they could complete the text without obstacles.

sangs rgyas is buddhas -- note again that there's no plural but later you will see why this is plural.
dang is the binding particle.
byang chub sems dpa' is bodhisattvas.
thams cad is all, so this is where the plural came fom.
la is the oblique particle, pointing at something from the right to the left.
phyag 'tshal is to pay homage, prostrate, relate to something, requesting the same realizations and qualities as the object one is prostrating towards, getting inspiration. As this is here a complete sentence, the verb is ended with a lo.

Parts of Khenpo Kunpal's excellent commentary of this text, translated by Andreas Kretschmar, is available here. Especially the introduction is fascinating, it goes through the history and lineages of various presentations of Bodhisattva Way of Life in India and Tibet.