There are two concepts here, that can make things confusing: time, and the flow of time.

Yes, time exists, and it can be measured precisely. Seconds, minutes and hours exist whether we want it or not. They are predictable, and you can make equations about them, such as predicting where some object will be in 5 seconds if you know its speed and some other characteristics.

Then there's the flow of time. Which is more of a metaphysical thing. We can only measure time relative to something else, for example a day is defined as the time it takes for our planet to make a full 360° rotation. But it doesn't explain why a day passes by at the rate we experience it.

What if everything in our universe suddenly happened 10 times faster? Our equations would still work, because a day would still be a day. Only we would experience it 10 times faster, and that is not something you can describe with equations. This flow of time is tightly linked to consciousness as it seems to fluctuate (like during sleep), suggesting it may not exist at all other than in our minds. But it doesn't invalidate the existence of physical time, the one you can plug in an equation and make it give predictable results.