Text can be aligned with one or both edges of a text frame. Text is considered as 'justified' when it is aligned with both edges.
You can choose to justify all text in a paragraph excluding the last line (Paragraph alignment = Justified, Last line alignment = Left), or you can justify text in a paragraph including the last line (Paragraph alignment = Justified, Last line alignment = Justify).
When you have only a few characters on the last line, you may want to use a flush space style. (See Align signature to the last text line .)
To align text vertically within a text frame, see Align signature to the bottom of the column, Align all text to the bottom of the column, Center text vertically in a column by tags, Spread lines in text vertically.
See also Toggle lock to the baseline grid.