Using the -text option will give you the full breadth of information.

openssl x509 -text -in cert.pem

Other options will provide more targeted sets of data.

# who issued the cert?
openssl x509 -noout -in cert.pem -issuer


# to whom was it issued?
openssl x509 -noout -in cert.pem -subject

# for what dates is it valid?
openssl x509 -noout -in cert.pem -dates

# the above, all at once
openssl x509 -noout -in cert.pem -issuer -subject -dates

# what is its hash value?
openssl x509 -noout -in cert.pem -hash

# what is its MD5 fingerprint?
openssl x509 -noout -in cert.pem -fingerprint