Assuming this is the algorithm for a Fibonacci number generator, it represents simultaneous/parallel assignment; the comma is not separating two statements, but two operands to the
i, j <- 1, both i and j are set to 1; it's just shorthand for
i <- 1 and
j <- 1, which could happen in any order.
i,j ← j,i + j, it means
i <- j and simultaneously
j <- i+j. It's necessary for both to happen at once, because you need to use the original values of both variables.
In a language without that facility, you'd have to introduce a temporary variable:
i2 <- i
i <- j
j <- i2 + j
j2 <- j
j <- i + j
i <- j2
This may be based on a real language with this syntax, or it may just be a convenience for the algorithms being discussed. For instance, sort algorithms will often be written in a pseudocode with a "swap" operator of some sort, rather than the full set of instructions needed in a particular language, in order to focus on the most relevant details.