Concept:
In coding–decoding problems, each letter of a word is replaced using a certain pattern or rule.
Here, every letter in the word is shifted one step forward in the alphabetical order.
Step 1: Observe the pattern in the given example.
\[
O \rightarrow P
\]
\[
R \rightarrow S
\]
\[
A \rightarrow B
\]
\[
N \rightarrow O
\]
\[
G \rightarrow H
\]
\[
E \rightarrow F
\]
Thus, each letter is increased by \(+1\).
Step 2: Apply the same rule to the word ‘GRAPES'.
\[
G \rightarrow H
\]
\[
R \rightarrow S
\]
\[
A \rightarrow B
\]
\[
P \rightarrow Q
\]
\[
E \rightarrow F
\]
\[
S \rightarrow T
\]
Step 3: Write the coded word.
\[
GRAPES \rightarrow HSBQFT
\]
Thus, the required code is:
\[
\boxed{HSBQFT}
\]