The Gyuto is a multi-purpose, large bladed knife that you can use for almost everything. Typically they range from 180mm to 240mm with 210mm being the most popular size due to it's sweet spot of length for larger tasks but excellent agility. 180mm is popular for smaller home kitchen tasks and 240mm is popular with professionals for long prep tasks.
The blade profile is great for cutting in a rocking type motion. If you are looking for one knife, this is the most versatile.