Upvote:1
In general, legalization is used to authenticate or certify a document so another country will recognize/accept it, e.g., certificates of birth, marriage, divorce; business contracts, export certificates. The site you've linked to is of a travel and tour company.
It directs you to apply directly to Taiwan's Bureau of Consular Affairs where what is required is clearer:
Visitor Visa for Visiting Purpose
- Completed & signed application form: Please access the website: https://visawebapp.boca.gov.tw/ to fill out application form online and print it out.
- Two passport-size photos in color within 6 months: Photos with a white color background
- Passport (original & photocopy): Valid for 6 months with blank pages
- Invitation Letter: Provided by inviting organization
- Evidence of funds: e.g. Bank statement
- Travel Itinerary
- Other additional documents may be required during processing: Ticket, electronic ticket or proof of a travel agency
Items which you may be asked to have legalized might be the copy of your passport and, possibly, the bank statements if not originals with each page stamped by bank officials.
You'll find the visa fees at document at the foot of the Visa Fees page, as a downloadable pdf.