Praise be to Allah.
Meaning of “la ilaha illa Allah”
Bearing witness “la ilaha illa Allah” and that “Muhammadun Rasul Allah” is the first pillar of the five pillars of Islam. And the meaning of “la ilaha illa Allah” is that nothing worshipped is worthy of worship except Allah—it is simultaneously a denial and affirmation. “la ilaha” is denial of all worship other than that of Allah. “illa Allah” is affirmation that all worship is for Allah Alone without partners.
Meaning of “Muhammad Rasul Allah”
As for the declaration, “Muhammadun Rasul Allah ,” its meaning is the assertion of the message of Muhammad (peace and blessings of Allah be upon him) and to believe in it and to adhere to it by speech, action and faith, and to avoid all that is against it, whether it be sayings, actions, or intentions.
In other words, obeying him in what he ordered and believing in what he said and relayed and avoiding what he has forbidden and denounced and not worshipping Allah except as he has ordained.
And Allah knows best.