Tissue cultured plants are small clones grown in a lab from an adult plant. They take the growth point (Probably from an attached pup?) and divide it into pieces add some hormones, etc. and make lots of new plants this way. There are some Tissue Culturists on this site that know more than me about it. Some places in the US that sells them are
Buy Banana Plants & More Tropical Plants For Sale, Florida Hill Nursery
Wellspring Gardens
They are small, usually under a foot tall, but sometimes bigger if you buy them at the end of the summer I have noticed. It takes a couple of years to get to fruiting size, but growth is usually pretty rapid and you can have a decent size plant to look at the first year. It depends on the variety though, I have had some ornamentals like Bordelon get about 7 foot the first year from tissue culture, while my Saba is still small 2 years later. Getting a pup would probably be preferable as far as how fast a plant grows, but TC plants are good when you cant find what you want as a pup, and usually arrive very quickly in the mail.