According to the Jewish laws, you are not allowed to work on the sevenths day and on holidays. Saturday in Hebrew is called Shabbat. On Shabbat and holidays, most of the stores and shops will be closed and there will be no public transportation aside from some exceptional.
As more religious the place you are, the more you'll feel the "you shall not work thing".
Usually in big cities restaurants and bars will be open on Shabbat. For example, In Tel Aviv which is mostly a secular place, most of the restaurants and bars will be open, in Jerusalem less of them.
According to the Gregorian calendar which is being used in the western world, the day changes at midnight. So if today is Friday, only at midnight the day will change to Saturday. According to the Jewish calendar, the day ends with the sunset. So if you are watching the sunset on Tel Aviv beach on Friday evening, once the sun is down it's already Shabbat.
So usually all the things that shut down on Shabbat will be closed something like 3 hours before Shabbat enters(at sunset). because it depends on sunsets, the exact time will be different from winter to summer.
So if Shabbat starts at sunsets...it also ends at sunset, Saturday evening sunset. Usually, things will be open around 1 hour after sunset.
the ceremony which closes Shabbat is called Havdala and you can experience it here.
Religious People - A total resting day
Religious people taking the resting thing to the extreme. according to the Jewish law, you can't light a fire, use electricity, money or even drive your car. Some people see it as madness, some people see it as a unique opportunity.
Imagine if once a week it will be a sin to check emails, facebook, watch television and YouTube. You are not allowed to use money so you can't go shopping, you can't drive your car, what you will do?
It forces you to actually rest, spend time socializing with family and friends, go for a walk or just be with yourself.
Secular People - Hiking, cycling, and beach
The secular people use the resting day for leisure activities. Their approach is I am working the whole week, on the weekend I'm doing my hobbies, go hiking, go to the beach and so... the religious people will say it is not a real rest, it is still hustling.
Makes one think what is a rest?
Saturday beach and hike are part of the secular people culture.
On Friday evenings as Shabbat enters there is a tradition to have a big dinner with family and friends. Religious people will say special prayers and will have a ceremony over the wine and the bread.
Most of the Israelis will do this Tradition even if they are not religious. Inviting friends/family over for a dinner. If you will get Local friends they might invite you to such dinners. Some of the hostels around the country do a Friday dinner for it guests.