okay if we're really doing Baby's First Interpreting Speech Acts then let's do this.
one of the slogans that got kicked around during the same sex marriage fight was "love is love" and obviously this is a deeply idiotic thing to say: it's a trivially true tautology! it conveys zero information! it might as well be "fish is fish" or "x = x"! if you're a baby who thinks that political slogans are literal statements of predicate calculus.
if you're an adult human being and you've been around the block a few times and had literally any exposure to human language and culture at all then you will immediately grasp that a slogan is a highly compact soundbite that acts as a symbol for a much more complex ideological statement, and this one is no exception.
"love is love" in the context of this debate expands to an assertion that marriage in the modern world is a relationship founded on love, and that love can be found between two people of the same sex, and this love is equally legitimate and valuable and deserving of the social and legal recognition that marriage is seen to confer.
more generally the same sex marriage fight was one battle in a much broader contest of worldviews as to whether being gay is something that society can accept, defend, even celebrate, or something that society must reject as a perversion of sick freaks, and "love is love" displays a very clear stand on that question.
(for a while people tried to hedge their bets with "what if we neither attacked it nor defended it" or "what if we just silently tolerated it" but that's an unstable equilibrium that has to fall one way or the other).
"trans women are women" is just as easy to unpack: it's an assertion that the social gender of women is not just occupied by cis women, whose social gender matches their biological sex at birth, but also by trans women, who have transitioned their social gender such that it differs from their biological sex at birth.
it's a claim that social transition is possible, and something that society should accept, defend, or even celebrate, and this is a mundane claim in the sense that it applies to social relations and doesn't have any metaphysical or supernatural implications.
(unless you want it to! and the catholics obviously take exception to gender transition and gay marriage on the same religious grounds).
if you're not willing to take a religious stance in opposition to these viewpoints then it puts you in a tough spot: to oppose gay marriage you have to insist that love really isn't love, that no gay relationship is worth defending or celebrating, or you have to admit that some gay marriages are "real" but their happiness must be sacrificed for the greater good, a tough sell but some people try.
similarly to oppose gender transition you have to insist that every trans man is a deluded straight woman or a sadly misled butch lesbian and every trans woman is an oppressed gay man or a perverted straight sex pest, or concede that maybe one or two are "really" trans but they too must suffer for the greater good.
this is pretty basic stuff! and it's good to get to grips with the actual issue instead of pretending that words don't make sense.