Complex sentence: It became the group's biggest hit in the U.S., reaching number four on the Billboard Hot 100 chart, but was not a major hit in the UK, where it only reached number 48 on the UK Singles Chart.
Split into simpler sentences: It became the group's biggest hit in the US, reaching number four on the Billboard Hot 100 chart. This popularity did not translate to their home country, where it reached number 48 on the UK Singles Chart.