In a general sense what does it mean when someone ends their text with the abbreviation LG followed by the first letter of their name?
Um welche Uhrzeit am Morgen wird er den Zug nehmen?
LG is an abbreviation for Liebe Grüße, and mainly used if you only have very little time or space (like text messages) to write an actual valediction.
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As mwil.me says, LG is just "Liebe Grüße". I have seen it in cases where lack of time or space seems very unlikely (say, an otherwise quite substantive email), and believe that some people simply always use that line so they don't have to think about different greetings for different levels of politeness/social distance.
I'm german :D
LG means Liebe Grüße in german