I like to think of it as “extra” money that I have to wait for. Specifically 2 years. Once the two years are up(vested) they give you shares of the company. Once you have said shares you can do two things, sell them or keep them. If you choose to sell them the selling price will be however 1 share of the company costs ($80 a share currently). I myself have 15 shares of the company so if a share sells for let’s say $100, that translates to $1500 if I were to sell them. So here’s where the incentive is to keep them, the better the company does, the value of a share will go up. I have been with the company for 4 years, when I first got my bean stock a share was valued around $60ish dollars but now it’s $80. What was once worth $600 for me is now worth $800 just from me being patient. However if the company isn’t doing too well the value of a share will go down. Meaning you’ll have less money.
Once the shares the company gave you have “vested” (2 years) those shares are now yours. You are free to do whatever you want with them. However, you do not get anything for terminating your employment with Starbucks before those shares have vested. So if you’re a year old partner and you quit, you get nothing.
I myself would highly recommend learning the basics of the stock market so you can make an informed decision with what to do with your bean stock once it’s vested.
Feel free to dm if I didn’t answer clearly enough or if you still have questions, I’d be happy to help!

There are a few different things you could be talking about. The default is that nothing is taken out, you have to opt in to all of these programs, and you can change your contributions at any time.

Stock grants are typically given at the end of the year. You just are given a certain number of restricted stock shares as a bonus at the end of the year. They are restricted shares, so you don't completely own them over a vesting period. After 1 year you own half and at the end of 2 years you own them all.

There's the bean stock, where you can purchase starbucks stock at a 5% discount. I would talk to a financial advisor about this option since it takes certain specific circumstances for most baristas to see much financial advantage from doing this.

Then there's the 401(k) plan. You get a 5% matching contribution to a retirement fund. So if you make $100 starbucks just gives you $5 put directly into your retirement account if you also put $5 in it.

I don't understand either