Hello there Marx,
I'll do my best to answer your question. I still consider myself a learner in this field but I know where the tones go intrinsically.
Panjabi has 3 tones: a high, a low, and a level. The low tone is produced after four different letters: gha (aspirated velar), jha (aspirated palatal), Dha (aspirated retroflex), dha (aspirated dental), and bha (aspirated labial). These letters carry a kind of falling tone with them. It is, in my opinion, the most recognizable tone to learners.
The level tone is, to my best knowledge, just the regular tone of speech. I don't think there is anything outstandingly different about about.
The low high tone arises from a combination of the letter "ha" and a vowel. It sounds like a rising tone.
The tones are very important, as there are some words which can be confused if you don't use them. But as with every language, there are dialects, and some dialects do not tonalize everything the same. For example, in the Pakistani dialect Multani, the letters "bha" and "dha" do not carry a low tone.
In my opinion, you can make yourself understood without the tones, but you may have some difficulty. People may think you are speaking Hindi and switch, or they may try and correct you (which leads to a hilarious game of confusion between the learner and the native, where the learner doesn't hear the difference between tone and no tone). To the best of my knowledge, Panjabi is the only South Asian language that has tones.
Thanks for your question! I certainly wish there was more interest in this language!