Complex sentence: Its picturesque mountain scenery and healthy mountain air make it an attractive destination for Europeans, especially Italians, not only in the winter for skiing, but also in the summer for hiking and relaxing.
Split into simpler sentences: Its picturesque mountain scenery and healthy mountain air make it an attractive destination for Europeans, especially Italians. It is popular not only in the winter for skiing, but also in the summer for hiking and relaxing.