Question

Please buy two _ (juices/juice cans)from the store.

Answer 1

sentence is in simple present tense,

We know, 

Simple present's formula,

subject + verb(s/es) + object

So



Please buy two 'juice cans' from the store,


scientificly,

juices is a liquid substance which can't be "two"

so, 

Again,

Please buy two juice cans from the store.


I hope this will help you

-by ABHAY


Please delete it...please.....on finding any mistake, 

Answer 2

$\begin{gathered}{\huge{\fbox{\fbox{\textbf{\textsf{{\color{navy}{An}}{\purple{sw}}{\pink{er}}}}}}}} \\ \end{gathered}$

➙ Please buy two juice cans from the store.