Pros and cons of teaching assistantship as a masters student intending to go on to industry job Background:
In the final year of my masters. Not seeking to apply for a PhD program in the future.

Situation:
I have a potential opportunity to TA a grad level course. Highly confused about taking it up. The opportunity is good however along with the 2 courses that I have to take for graduation, I also wanted to take up another extra course to gain new skills for use in the industry.

Ideally I would want to do both - the extra course and also the TA work. However since I have not taken up a TA opportunity before, I fear balancing 3 courses + the TA work would be a potential overload. However once I leave grad school, I won't be able to have a TA opportunity nor will I be able to take the extra course that is offered here. The TA work would be around 15-20 hours per week. I also have to pay for the extra course I take up.

Any ideas/suggestions would really help. Answers from an industry standpoint would really help.
I can't really comment on the financial side, that all depends on your own financial situation. The main advantage of TAing, besides the money, is that if you want to teach in the future in any capacity then getting some experience teaching is vital. If you don't plan to teach in the future, then the work experience is probably negligible. There are probably some "soft" benefits that could be useful in industry, such as learning to effectively condense and explain material in your field, but I doubt they would be very helpful in terms of getting hired.

In terms of balancing work, that also mostly depends on the courses and your own productivity. I will say that at many PhD programs, 3 courses + a 15-20 hour TAship is a pretty standard workload for the first couple years (assuming you don't do significant research your first year or so), so it's probably doable.