Complex sentence: "Hold On" reached No.1 on the Billboard Year-End chart for 1990 as the top R&B hit, and as the No.8 pop hit on the Billboard Year-End chart.
Split into simpler sentences: Hold On reached No.1 on the Billboard Year-End chart for 1990 as an R&B hit. As a pop hit, it also reached No.8 on that portion of the Year-end chart.