Complex sentence: In New Zealand, the name "Sellotape" is also used as a colloquialism for the adhesive tape, and is manufactured locally by Henkel New Zealand, which is the biggest selling brand of adhesive in that country.
Split into simpler sentences: In New Zealand, the name "Sellotape" is also used as a colloquialism for the adhesive tape, and is manufactured locally by Henkel New Zealand. It is the biggest selling brand of adhesive in that country.