what is meaning of below c++ map means ?

[Qt embedded developer]

In below code i am not understanding the concept of the below statement :

sqliteManagerMap.insert(std::pair<int,SqliteManagerBGSync>(threadId,new SqliteManagerBGSync()))*

can any body explain me it theoretically. what this statement do ?

namespace app
{
namespace dbmanager
{
std::map<int,SqliteManagerBGSync *> SqliteManagerBGSync::sqliteManagerMap;
SqliteManagerBGSync::SqliteManagerBGSync()
{
	DBGF_TRACE("AFCS:SqliteManagerBGSync::Constructor Called");
	handle = NULL;
}

SqliteManagerBGSync* SqliteManagerBGSync::GetDBInstance()
{
	std::map<int,SqliteManagerBGSync*>::iterator it;
	int threadId = pthread_self();
	DBGF_TRACE("AFCS:SqliteManagerBGSync::thread Id :%d",threadId);

	//sqliteManagerMap.empty() Return 0 If sqliteManagerMap is Not Empty
	//Return 1 If sqliteManagerMap is Empty
	DBGF_TRACE("AFCS:SqliteManagerBGSync::GetDBInstance()::sqliteManagerMap.empty()=%d",sqliteManagerMap.empty());

	if(sqliteManagerMap.empty())
	{
		DBGF_TRACE("AFCS:SqliteManagerBGSync::GetDBInstance()::sqliteManagerMap.empty() IF");
		if(pthread_mutex_init(&databaseLock, NULL) != 0)
		{
			DBGF_TRACE("databaseLock mutex init failed");

		}
		else
		{
			DBGF_TRACE("databaseLock mutex init Success");

		}
	}
	it = sqliteManagerMap.find(threadId);
	if(it == sqliteManagerMap.end())
	{
		DBGF_TRACE("AFCS:SqliteManagerBGSync::GetDBInstance()::threadId Find Success");
    
		sqliteManagerMap.insert(std::pair<int,SqliteManagerBGSync*>(threadId,new SqliteManagerBGSync()));
		DBGF_TRACE("AFCS:sqliteManagerMap insert called");

		it = sqliteManagerMap.find(threadId);
	}
	DBGF_TRACE("AFCS:SqliteManagerBGSync::sqliteManagerMap success return 2");

	DBGF_TRACE("SqliteManagerBGSync::GetDBInstance _heap_max() = %d",_heap_max());
	DBGF_TRACE("SqliteManagerBGSync::GetDBInstance _heap_current() = %d",_heap_current());

	return it->second;
}

[KroMignon]

@Qt-embedded-developer said in what is meaning of below c++ map means ?:

In below code i am not understanding the concept of the below statement :
sqliteManagerMap.insert(std::pair<int,SqliteManagerBGSync>(threadId,new SqliteManagerBGSync()))*
can any body explain me it theoretically. what this statement do ?

As described in std:map documentation => https://www.cplusplus.com/reference/map/map/insert/
It insert a new item in to map.