Mở tài liệu Excel. Nhấp vào nút "Select All" (Chọn tất cả). Nhấp vào thẻ Home nằm ngay bên dưới ruy-băng xanh lá ở đầu cửa sổ Excel. Nhấp vào Format (Định dạng). Chọn Hide & Unhide (Ẩn & bỏ ẩn). Nhấp vào tùy chọn Unhide Rows (Bỏ ẩn dòng) trong trình đơn bật ra.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Double-click the Excel document that you want to use to open it in Excel. This triangular button is in the upper-left corner of the spreadsheet, just above the 1 row and just left of the A column heading. Doing so selects your entire Excel document. You can also click any cell in the document and then press Ctrl+A (Windows) or ⌘ Command+A (Mac) to select the whole document. This tab is just below the green ribbon at the top of the Excel window. If you're already on the Home tab, skip this step.