John 8:7

ὡς δὲ ἐπέμενον ἐρωτῶντες αὐτόν, ἀνέκυψεν καὶ εἶπεν αὐτοῖς Ὁ ἀναμάρτητος ὑμῶν πρῶτος ἐπ’ αὐτὴν βαλέτω λίθον·

Rough Word-by-word:
as and they were continuing asking him, he stood up and he said to them, "The sinless of you all first on her you throw a stone."

Smooth Translation:
And as they were continuing asking him, he stood up and said to them, "The sinless man of you be first to throw a stone on her."

Notes:
πρῶτος does not modify "stone" or it would be accusative so it must modify "sinless man" or be a predicate adjective. So we are not talking about the first stone, but rather the first man to throw one.

ὡς conjunction "as"

δὲ post positive conjunction "and/but"

ἐπέμενον imperfect active indicative 3rd plural from ἐπιμένω (I remain on, I continue) "they were continuing"

ἐρωτῶντες present active participle nominative plural masculine from ἐρωτάω (I ask) "asking"

αὐτόν pronoun accusative singular masculine "him"

ἀνέκυψεν verb aorist active indicative 3rd singular from ἀνακύπτω (I stand up) "he stood up"

καὶ conjunction "and"

εἶπεν verb aorist active indicative 3rd singular from λέγω (I say) "he said"

αὐτοῖς pronoun dative plural masculine "to them"

Ὁ definite article nominative singular masculine "the"

ἀναμάρτητος adjective nominative singular masculine "sinless [man]"

ὑμῶν pronoun genitive 2nd plural "of you"

πρῶτος adjective nominative singular masculine "first"

ἐπ’ preposition with accusative "on"

αὐτὴν pronoun accusative singular feminine "her"

βαλέτω verb aorist active imperative from βάλλω (I throw) "you throw"

λίθον noun accusative singular masculine "[a] stone"