Are Helios lenses conpatible on Pentax film cameras?

Yes, the thread mount versions (M42) are compatible with older Pentax cameras using the same mount, the K-mount versions are will fit newer Pentax cameras.
You can easily distinct them by the name:
e.g. Helios 44M-4 is M42 screw mount
https://www.pentaxforums.com/userreviews/data/83/K5JH4306.jpg
Helios 44K-4 is the K-mount version.
https://www.pentaxforums.com/userreviews/data/83/1111.jpg
Therer are also adapters to use screw mount lenses on K-mount bodies.
Mind that older screw mount versions of Pentax cameras might not support automatic lenses (the ones with a pin that moves the aperture). You can easily determine that by looking into the camera with the lens removed. If there is a crescant shaped lever on the bottom side of the the opening it will support automatic lenses.
If not you need either a preset lens Helios up to version 44-2 or one that can be switched between A/M like the Helios 44-3. These older versions exist only in M42 screw mount.

Hope this helps and have fun using your Pentax film camera

Helios screwmount (M42) lenses will work with Pentax screwmount cameras (Spotmatic lineup) and with K-mount models with an adapter (get the one that's flushed on the body not raised to be able to focus to infinity). With screwmount cameras, you will have a problem with finding the right battery for the lightmeter. Most used mercury types which are now banned. Anywho, just use one without the lightmeter and shoot using the Sunny f/16 way.