אֲ-דֹנָי שְׂפָתַי תִּפְתָּח וּפִי יַגִּיד תְּהִלָּתֶךָ

א-דני שפתי תפתח ופי יגיד תהלתך

MY MASTER, YOU SHOULD OPEN MY LIPS AND MY MOUTH SHOULD RELATE YOUR PRAISE

This can be simply understood as a תפילה to Hashem to help us direct our thoughts and our speech – to daven properly – “to open our lips to relate Your praise”.
But it’s much deeper than that. א-דני שפתי תפתח – We entreat Hashem, “Without You, Hashem, I cannot even open my lips, not for anything, let alone to praise You. And therefore, ופי יגיד תהלתך, my lips that you have opened are dedicated to You, solely for the purpose of relating Your praise” – our lips and mouths are for our Master.