These two IE are for Bandwidth part configuration.Bandwidth parts are configured per serving cell for uplink (if the serving cell is configured with an uplink) and for downlink.
firstActiveUplinkBwp-Id & firstActiveUplinkBwp-Id-->BandwidthPartId. ID of the uplink & downlink. bandwidth part to be used upon MAC-activation of an SCell. If not provided, the UE uses the default BWP( bandwidth part).