Lambda Expressions Clarification

In the first lesson of Lambda Expressions, how are the lambda expressions being defined? will the first array parameter being placed as the method’s parameter?

This is the example used:

string[ ] spaceRocks = {“meteoroid”, “meteor”, “meteorite”};

  bool makesContact = Array.Exists(spaceRocks, (string s) => s == "meteorite");

So would the variable ‘s’ be defined by the elements in the ‘spaceRocks’ array?