Complex sentence: There are thousands of freight companies in the world, many of which are members of certain organisations, such as IATA (International Aviation Transport Association), BIFA (British International Freight Association), FTA (Freight Transport Association) and various or other regional organisations.
Split into simpler sentences: There are thousands of freight companies in business worldwide, many of which are members of certain organisations. Such organizations include the IATA (International Aviation Transport Association), the BIFA (British International Freight Association), or the FTA (Freight Transport Association) and various or other regional organisations.