Single stream means sequence delivery of data where as multi stream means sequence delivery of the data within a stream only and data belongs to different stream can be delivered independently of this stream.
So in short This feature of SCTP allows data to be partitioned into multiple streams that have the property of independently sequenced delivery, so that message loss in any one stream will only initially affect delivery within that stream, and not delivery in other streams. This was a problem of TCP and was known as Head of Line blocking. (TCP assumes a single stream of data and ensures that delivery of that stream takes place with byte sequence preservation. While this is desirable for delivery of a file or record, it causes additional delay when message loss or sequence error occurs within the network. When this happens, TCP must delay delivery of data until the correct sequencing is restored, either by receipt of an out-of-sequence message, or by retransmission of a lost message.)
In pcap you can look at in-coming stream id and outgoing stream id for more detail please attach the image of PCAP.