B'seder is one of the most frequently used words in colloquial Hebrew. It more or less translates as "OK", but it is used in so many contexts and in so many tones of voice that I have a hunch it's a simple word with several layers of meaning. And many Anglos in Israel will complete their sentences, spoken in English, with a b'seder, as if that single Hebrew word can summarize or encapsulate all of the words that preceded it.
The basic use is to affirm that everything is all right. For example, "Shall we meet for coffee at 4pm?" a friend asks. "B'seder," is the response. One also can say, "B'seder" to the frequently asked, "How are you?" And wandering around various shops and stores with, perhaps with a serious expression on my faced, people have asked me, "Is everything b'seder?", as in, "Are you OK?". "B'seder," I reply.
But there are more interesting uses. One of my teachers at Pardes (Institute of Jewish Studies), commenting in English on an Israeli cabinet member's views on prisoner exchanges, concluded that the man was b'seder, meaning competent and intelligent.
A woman outside the Jerusalem Central Bus Station, upon seeing a group of young policemen enter the building, angrily reprimanded them, "You are not b'seder!", suggesting that they are inept or, worse, unethical. They said nothing.
After the bus driver to Eilat lost his temper with boarding passengers, yelling at basically everyone, I fastened my seatbelt and commented to my neighbor, "If he's in such a bad mood he might take it out on the road." She said, "No, no, he's b'seder. I rode with him a month ago and when the bus broke down he dealt with it well," suggesting that underneath his ferocious exterior he was, after all, a mensch, someone who can be trusted to behave appropriately in a difficult moment.
And I've heard many cell phone conversations in which the intense repetition of b'seder suggests that, maybe, things really aren't all that OK but the person just wants to get on with it. The drawn out, somewhat resigned pronunciation, buh..sayder, indicates that the speaker has capitulated.
Then there's b'seder gamoor, which is, "Everything is completely fine (period, full stop)." It's a definitive way to wrap up a line of questioning or a conversation.