A +1.5 spread is commonly seen in baseball betting, the standard runline  for MLB. This spread means the underdog must win outright or lose by exactly one run to cover the spread. Alternatively, a -1.5 spread means that the favorite must win by at least two runs. Many baseball games are decided by fewer than two runs.
Yes, bet365 is a trustworthy online gambling site. They are licensed and regulated by the UK Gambling Commission and have been in business since 2001.