How can I find and click elements in my calendar?

Where’s number2 ?

I’m not an xpath guru, but this CSS selector should target the td-element you highlighted in your screenshot:

div#schedulerSch .k-scheduler-content>table td:nth-child(5)

To prove it works, try something like this in the browser console:

document.querySelector("div#schedulerSch .k-scheduler-content>table td:nth-child(5)").style.outline = "thick solid orange"