What is the meaning of "The transistors Q1,Q2 are identical" and of "Q1/Q2 = 10"
Two transistors Q1,Q2 are identical


Unfortunately you do not describe in which context this statement is made.

I have seen such statements before in the context of analog IC design. On a chip we can make transistors that are "identical" in the sense that they have very similar transistor parameters like \$\beta\$ and what \$V_{BE}\$ you get under certain circumstances.

This has nothing to do with "external parameters" like \$V_{CE}\$ because these are mostly defined by the circuit in which a transistor is used.

On an IC transistors can be identical as they're all made at the same time.

Discrete transistors can be identical but you'll have to do your best to find a pair that  is identical enough. You might never find a pair like that.

The most basic application of "identical" transistors is a current mirror:



Where TR1 converts I1 into a (\$V_{BE}\$) voltage which is then applied to an identical transistor TR2 which then makes a copy of I1 flow, which is I2.

For identical transistors I1 = I2 (ignoring some 2nd order effects).