"Peter has to meet Julia."
Translation:पीटर को जूलिया से मिलना है।
To say 'has to'/'have to' in Hindi, we usually use the verb infinitive+है construction. While doing so, the noun has to be followed by को.
Eg: Raj has to eat - राज को खाना है।
So, 'पीटर को मिलना है' would be 'Peter has to meet'. Of course, this is not a valid statement without specifying who he has to meet so we add ' जूलिया से'='with Julia' as the indirect object of the verb मिलना.
Take a second look at Vinay92's comment above from 9-August-2019. If that doesn't help, there's more discussion here: https://forum.duolingo.com/comment/29456405/आमिर+को+मेरे+घर+आना+है।