What the score is for
Ashtakoot (Guna Milan) compares Moon-based factors between two charts. Families historically used it as one filter among many. A high total does not guarantee harmony; a lower total does not forbid a relationship.
What to weigh besides the number
Manglik / Kuja flags, Nadi considerations, and the full charts of both people matter more than a single integer. On Vedic Kundli you can open dual Manglik notes and optional private browser notes under matching results.