Makes it harder to talk to people you don't know, but not impossible. Can make it harder to speak up in group unless you really know people. May cause people to boss you around or take over.
Social anxiety - aka social phobia - is different:
Anxiety is severe, and may even cause panic attacks. Thinking about a social function causes anxiety, even before you're there. Interacting with anyone causes extreme fear and doubt. Any perceived mistake may lead to shame, depression, and further negative emotions. Causes you to feel very negative, and may make your life much more difficult.
Social phobia is an extreme version of shyness. While there are several types of differences, the biggest is simply the person’s contentment level with their life. If you are practically disabled by social situations, chances are you have social phobia. If you are generally fine but very quiet around other people and only a little bit prone to embarrassment, chances are you’re simply shy.