In problem of leetcode if two strings are close I got solution as

class Solution {
unordered_map<char, int> m1;
unordered_map<char, int> m2;

set<char> sc1;
set<char> sc2;

multiset<int> s1;
multiset<int> s2;

public:
    bool closeStrings(string word1, string word2) {
        ios_base::sync_with_stdio(false);
        if(word1.size() != word2.size()) return false;

        for(auto& x : word1) m1[x]++;
        for(auto& x : word2) m2[x]++;
        
        for(auto it = m1.begin(); it != m1.end(); it++) {
            sc1.insert(it->first);
            s1.insert(it->second);
        }

        for(auto it = m2.begin(); it != m2.end(); it++) {
            sc2.insert(it->first);
            s2.insert(it->second);
        }

        return sc1 == sc2 && s2 == s1;
    }
};

as this code. what does the == sign checks ?Thank u all in advance

Pls make me understand the use of this operator