What is meant by "reproduction" in the description of this exercise? In the following exercise, the word reproduction is mentioned.

Your task is to design a simple genetic algorithm, with binary-coded chromosomes, in order to solve a pattern-finding problem in 16-bit strings.
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You may use the following operators:

Reproduction: You can use either one of the following reproduction types: Proportional, Ranking, Tournament.




Crossing over: In order to perform this operation the individuals must be grouped in pairs (randomly), and, with certain probability p, cross information from their chromosomes must be exchanged.




Mutation: This operator changes the value of each bit in the chromosome to the opposite one with a very small probability


So, apparently, crossover and reproduction do not refer to the same concept. What does the word reproduction refer to in a genetic algorithm and in this exercise?
The terminology of this exercise is not standard. What is referred to as "reproduction" in the exercise is usually referred to as "selection".

The term "reproduction" does indeed seem conceptually closer to the notion of crossover or recombination (these two are the same thing), which is probably where your confusion has arisen.

See the excellent (and freely-downloadable) 'Essentials of Metaheuristics' for an introduction to the usual terminology for evolutionary algorithms.