Disambiguation: Mac does have a "task manager" of sorts
On Windows, Task Manager is a system utility you open with Ctrl+Alt+Delete. It shows running processes, CPU and memory usage, and lets you force-quit programs that have stopped responding. macOS has an equivalent called Activity Monitor, but the name does not match, which is why many people search for "Mac task manager" and end up on productivity app review pages instead of finding what they actually wanted.
To open Activity Monitor on a Mac: go to Applications, then Utilities, then double-click Activity Monitor. Alternatively, press Cmd+Space to open Spotlight, type Activity Monitor, and press Return. Once open, you will see a list of every process running on your Mac, with columns for CPU percentage, memory footprint, energy impact, disk activity, and network usage. You can sort by any column, filter by process name, and force-quit a frozen app by selecting it and clicking the X button in the toolbar.
If that is what you were looking for, you are set. If you came here because you want a better to-do list app for macOS, read on.