noun
English letter; alphabetic character
Refers to letters of the English alphabet, as opposed to Japanese kana or kanji.
パスワードは英文字と数字を組み合わせてください。
Please combine English letters and numbers for your password.
この書類は英文字で記入してください。
Please fill out this form in English letters.
アルファベット is a broader term for any alphabet, but often used for the English alphabet. 英文字 explicitly ties the letters to English.
Compound of 英 (English) and 文字 (letter, character).