Is it possible to use this phrase to ask how a specific thing is going? For example somebody just started a new study and you want to ask how that's working out for them. In English, I would feel comfortable asking 'And how's that going?'. This translation is not accepted here, but I wonder if in Czech you could use the phrase 'Jak to jde?' or 'Jak to de?'
My father, the youngest of 7 children, was the only one born in the US. The other siblings and parents were born in Moravia. This predates Czechoslovakia. I remember my father saying something that my ears took as "Yak shemash". He has passed on and I eventually realized that he was saying Jak se máš?
What about how is it? Because for me how is it going somehow doesn't feel as someshing you would say in english. As an alternative for how are you, because jak to jde does not exactly mean that, it could mean that but it could also be like i'm implying, how is it with... ( something that's not written here, like how is it at home with you).
"How's it going?" is said quite commonly in (US) English.
On the other hand, "how is it?" is more akin to "what is it like?", e.g. "How is the sandwich you're eating?" and that's not how "Jak to jde?" is used.
"Jak to jde?" is a colloquial way of saying "How are things (with you, your life, etc.)?" or "How are you faring at the thing that you're currently doing?" -- both of these are well expressed by "How is it going?"