As a prefix meaning 'next' or 'coming' (e.g., next year, next spring); used in Sino-Japanese compounds (reading: らい).
来年から大学で勉強を始める予定だ。
I plan to start studying at university from next year.
来月は出張が多くて忙しい。
Next month I'll be busy with many business trips.
来春には新しいプロジェクトを始めるつもりだ。
I intend to start a new project next spring.
As a suffix indicating duration 'since' or 'for' (e.g., '二十年来' meaning 'for twenty years' or '先月来' meaning 'since last month'); shows continuity from a point in time.
彼は二十年来の友人だ。
He has been a friend for twenty years.
先月来、体調がすぐれない。
Since last month, I have not been feeling well.
この町は戦後来、大きく変わった。
This town has changed a lot since the postwar period.