how do i go through a list and merge some phrases conditionally?

You can just use a traditional for loop like this:

phrases = [
   'Title',
   'page',
   'Specification',
   'High speed drilling ma-',
    'chine is aimed at'

]
index_lst = []
merged_phrases = []
for index,phrase in enumerate(phrases):
    if index not in index_lst:
        if phrase[-1] == '-':
            merged_phrases.append(phrase[:-1]+phrases[index+1])
            index_lst.append(index+1)
        else:
            merged_phrases.append(phrase)

print(merged_phrases)

Output:

['Title', 'page', 'Specification', 'High speed drilling machine is aimed at']

Edit:

If consecutive words in your list have - at the end, then you can use this code:

phrases = [
   'Title',
   'page',
   'Specification',
   'High speed drilling ma-',
   'chine is aimed at-',
   ' test-',
   ' 123'
]
index_lst = []
merged_phrases = []
for index,phrase in enumerate(phrases):
    curr_phrase = ''
    if index not in index_lst:
        for i,x in enumerate(phrases[index:]):
            if x[-1] == '-':
                curr_phrase += x[:-1]
                index_lst.append(index+i)
            else:
                if curr_phrase != '':
                    merged_phrases.append(curr_phrase+x)
                    index_lst.append(index + i)
                else:
                    merged_phrases.append(phrase)
                break

print(merged_phrases)

Output:

['Title', 'page', 'Specification', 'High speed drilling machine is aimed at test 123']