Tuplet numbers and ratios are very similar: both indicate the number of equal notes included in the tuplet, such as 3 for triplets, but tuplet ratios also include the number of normal notes into whose duration the tuplet fits, such as 3:2 for triplets.
Additionally, tuplet ratios can include a note glyph that indicates the duration of notes in the tuplet.
Tuplet numbers/ratios help performers quickly identify the type of tuplet and how they must fit the number of notes indicated into the prevailing tempo and meter.
In Dorico Pro, you can change the appearance of all tuplet numbers/ratios project-wide on the Tuplets page in Engraving Options, such as changing the font used for them, and for individual tuplets independently of this setting.
You can use properties in the Tuplets group of the Properties panel to edit individual tuplet numbers/ratios; however, the Tuplets group is only shown if you select tuplet numbers/ratios or brackets. It is not shown if you select notes within the tuplet, or notes within the tuplet and the tuplet number/ratio or bracket.