Complex sentence: He started playing professionally in Spain, for CD Leganés and UD Salamanca, scoring 20 goals with the latter in the 2001--02 season--spent in the second division--second-best in the competition.
Split into simpler sentences: He started playing professionally in Spain, for CD Leganés and UD Salamanca. With the latter, he scored 20 goals in the 2001--02 season, spent in the second division, second-best in the competition.