def num_words_tags(tags, data):
    """This functions takes the tags we want to count and the datafram 
    and return a dict where the key is the tag and the value is the frequency
    of that tag"""

    tags_count = {}

    for tag in tags:
        len_tag = len(data[data['Tag'] == tag])
        tags_count[tag] = len_tag

    return tags_count