How closely does the jewish calendar coincide with the solar calendar every 19 years? be specific and explain.

Throughout the 19 year cycle, there are occasions when a month is added to the Jewish year in order to maintain an alignment with Jewish holidays and seasons. This is learnt because it is said that Passover is the holiday of spring. 
Even though the Jewish calendar is based primarily on the lunar calendar (each new month is begun at a "new" moon), this makes it partially a solar calendar as well.
Every 19 years the same days align with the Jewish and Solar calendars.