Straight lines and organized grids help organize information on a screen and make the design look clean and consistent. Aligning text can also make text more readable.
Text can be aligned in a few different ways and it depends on the language you’re writing. For languages read from left to right (like English, Spanish, French, etc), you should align left. For languages read from right to left (like Farsi, Arabic, Hebrew, etc), you should align right.
You can also center or justify text, but I’d avoid them both. Centering text makes it hard to read because it creates ragged edges (each line starts at a different left edge). Justifying text fixes this problem and creates consistent lines on the outsides of the body, but it’s nearly impossible to learn, track, and letter spacing in a responsive way.
Lastly, let’s discuss aligning elements to each other. For this, I’d recommend using the typical 12 column grid with a small gutter. Here's a great intro video!