"His writing is hard to decipher because it is so messy."
- "His writing is so messy it's hard to decipher."
"his writing" 「彼の字」・「彼の書き方」
"so messy" 「すごく汚い」
"his writing is so messy" 「彼は風変わりな字を書く」
"it's hard to ~" 「〜が難しい」
"to decipher" 「判読する」
- "His writing is hard to decipher because it is so messy."
"his writing is hard to decipher" 「彼の字を判読が難しい」
"because it is so messy" 「すごく汚いから」